Teeth Whitening

The basic concept of teeth whitening, is the bleaching of the outer layer of teeth to remove stains that have penetrated into them, so that your teeth colour can lighten by various shades.

a) Trauma: When a tooth is injured, it reacts by depositing more dentin, a yellowish layer beneath the enamel. Your tooth may change colour due to an internal injury, so it is advised to visit your dentist if you suspect any injury. Internal discolourations may require internal whitening to lighten the teeth.

b) Medications: Tooth darkening can be a side effect of certain antihistamines, antipsychotics and high blood pressure medications. Children who are given certain antibiotics during the development of their teeth may experience the discolouration in their permanent teeth. Chemotherapy and head and neck radiation can also darken teeth. These types of internal discolourations are more difficult to whiten.

c) Sometimes, teeth turn yellow due to the surface of our teeth (the enamel layer) wearing out. This can be due to physical abrasion from harsh particles and heavy brushing or can be linked to acid erosion. Once thinned, the effect is permanent as your enamel layer cannot grow or thicken. Teeth whitening procedure can improve the colour, but there will be limitations to the results.

d) Age: Below the hard, white outer shell of your teeth (enamel) is a softer area called dentin. Over time, the outer enamel layer gets thinner with acids and brushing, and more of the inner yellowish dentin shows through. The inner layer also gets yellower with age, and this also exacerbates the yellow appearance of the teeth.

There are 2 different types:

1. The Take Home Whitening method, where your dentist will be take a scan of your teeth to create a customised whitening trays. These trays are thin and light to wear. You add a small amount of whitening gel to the tray and wear them from two to six hours per day or overnight until the desired whitening is achieved. This process usually takes two weeks. The trays are kept and can be used again for touch-ups.
2. The In Office Treatment is where the teeth are professionally whitened with a high concentration whitening gel, with results seen immediately after the treatment.

Over 10 years of clinical use of teeth whitening products containing 10% carbamide peroxide have not shown any damage to existing fillings.

However, please take note that whitening does not work on existing restorations such as tooth-coloured fillings, crowns, bonding, veneers, and bridges.

This means that any pre-existing dental work may appear darker after teeth whitening, as only your natural teeth will lighten. These restorations may need to be replaced afterwards to match the new tooth shade achieved.

Teeth whitening does not cause damage to the structure of the teeth. Studies of teeth whitening products using 10% carbamide perixide showed no effect on the hardness or mineral content of a tooth’s enamel surface.

Many factors play into the length of time that teeth whitening lasts. For example, smokers or those who drink beverages that stain teeth, such as red wine or coffee, may not have the same long-lasting effects as those who do not smoke or drink those beverages.

Results following teeth whitening can last from 6 months to 2 years, depending on the potency of the treatment and how well one can maintain their oral hygiene. 

Reducing exposure to staining agents like the ones mentioned above will reduce the rate at which the teeth stain again and prolong the whitening effect.

Temporary tooth sensitivity can occur after the teeth whitening process, but it typically subsides after a few days. You can try to avoid cold or sour food or drinks, and use sensitive toothpaste to reduce sensitivity. The intensity and length of time associated with tooth sensitivity after whitening varies by patient.

It’s best to have realistic expectations before undergoing any whitening treatment. Your dentist should be able to explain what to expect with whitening.

Not all whitening treatments are equally effective on all people, and not all teeth will whiten to the same degree.

Teeth whitening can change a tooth’s colour by several shades, meaning teeth that are more stained or discoloured won’t whiten to the same degree as teeth that were whiter originally.

It also depends on the structure of your teeth as to how effective the teeth whitening will be.

Teeth whitening has become a popular way to prepare for weddings and other social events where people want to look their best. But because some treatments can take time to be effective, you should make sure you leave enough time before the big day.

Home whitening kits using gels can take up to two weeks to achieve results. If you have your teeth whitened professionally by your dentist (sometimes called an “in-chair” treatment), the treatment may be completed in a single appointment of about 1-2hours.

If you have an oral health condition such as tooth decay or gum disease, this should be treated as a priority before arranging a cosmetic treatment. If you haven’t had a cleaning done for a while, this will need to be done before the whitening so as to allow the gel to contact your teeth properly.

Your dentist will let you know what to expect from teeth whitening and if you are able to have teeth whitening done. When you’ve found out what the treatment involves and what the possible side-effects are, you’ll be in a position to judge whether teeth whitening is the right option for you.

Everyone responds differently to whitening treatments and everyone will whiten at different rates.

Stains that have recently formed are easier to treat than those that have been present for many years.

Teeth that are yellow or brown tend to respond better to whitening than teeth that are grey in colour.

Younger patients typically whiten more quickly than older patients, but do know that every patient is different and results will vary across individuals.

When whitening, keep in mind that your smile looks most natural when the colour of your teeth matches the whites of your eyes.

Some people want a Hollywood white smile, which is usually whiter than what natural teeth can achieve. In such cases, it may be worthwhile to consider ceramic veneers as an option, as they can be made to a much whiter shade if you desire, and they do not change in colour over time.

1. Tooth Whitening: Facts and Fallacies
   H Heymann – (https://www.nature.com/articles/4812298)

2. Us6783363b2 – Discolored Teeth Bleaching System
   (https://patents.google.com/patent/US6783363B2/en)

3. In-office vital tooth bleaching–what do lights add?
   (https://europepmc.org/article/med/12793211)

4. Three-Month Evaluation of Vital Tooth Bleaching Using Light Units—A Randomized Clinical Study
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5. Effect Of Light Energy on Peroxide Tooth Bleaching
   Karen Luk-Laura Tam-Manfred Hubert – (https://www.sciencedirect.com/science/article/abs/pii/S0002817714639337)

6. Effect Of Bleaching Agents on the Microhardness Of Tooth-colored Restorative Materials
   Arzu Mujdeci-Osman Gokay – (https://www.ncbi.nlm.nih.gov/pubmed/16616125)