10 Things You Need to Know about Tooth Whitening

Dental Designs Clinic Singapore
27 Sep, 2022

Ever wanted pearly whites like your favourite movie stars? Tooth whitening can provide you with a bright and white smile that you can confidently show and make a great first impression.

How does tooth whitening work?

Tooth whitening uses bleaching agents to lighten the colour of your teeth. The tooth is semi-permeable. This allows for the tooth whitening chemicals, which are carbamide peroxide and hydrogen peroxide, to permeate into the tooth enamel, which removes the extrinsic and intrinsic stains.

How much improvement to the whiteness can I expect to see?

The extent of whitening and brightening of the teeth is reliant on the individual tooth condition and also the cause of discolouration and whether following the dentist’s instructions was carried out. Your dentist will be able to guide you to achieve a shade of white which you will be happy with after treatment, and will consult with you before the treatment starts to diagnose and plan your treatment.

Correct stained or discoloured teeth

Our teeth colour is due to the layer of tooth enamel on each teeth. Teeth may be intrinsically discoloured as tooth enamel also naturally come in different shades varying from light yellow to off white.  Teeth may be extrinsically discoloured due to lifestyle factors such as heavy smoking, or food consumption habits such as coffee, tea, red wine or coke. Teeth also discolour with age and darken or turn yellow with increasing age. The age-related discolouration is due to long term exposure to extrinsic discolouration and tooth structure. It is becoming increasingly common for older people who want to look younger to opt for tooth whitening

There are three treatment options for you to considerclose up teeth whitening before after

Immediate in-office whitening, take-home whitening kits, and comprehensive tooth whitening which comprises both in dental office whitening and take home whitening kits. Let’s explore each of these options.

Immediate in-office whitening offers you instant results.

By opting for immediate in-office whitening, you will see a brighter smile of at least 2-4 shades whiter than your current teeth. A laser or light activated whitening gel is used and a laser is shone into the mouth which results in an accelerated whitening process. Your lips and gums are protected from the bleaching agent with rubber seals or gel that the dentist prepares beforehand. You may expect mild to moderate sensitivity. It takes about an hour to happen and most of the treatment time can be spent. Multiple sessions may be required for increased brightening results if the starting shade is very dark. Maintenance of tooth whitening includes avoidance of staining food and drinks, good oral hygiene such as brushing and flossing, regular dental cleaning visits, and occasional bleaching touch-ups may be required to keep your smile bright and white.

Take home whitening kits offer gradual whitening with minimal sensitivity.

The dentist will fit you by taking a mould of your teeth for custom-fit trays and instructions on how to use the trays with the bleaching gel tubes. The gel is filled into the custom-fit trays and worn at home between an hour to overnight depending on your dentist’s instructions. The gel-filled trays are needed to be worn for two to four weeks continuously, during which it is advised to avoid staining food and drinks. There is minimal teeth sensitivity with this method of tooth whitening. You are also able to whiten tooth shades according to your preference as the process is gradual. The gel tubes are able to be purchased on their own from your dentist in order to maintain the whiteness of your teeth throughout the years.

Can I treat a single dark tooth?

A single dark tooth is usually due to two factors. The first factor is due to root canal treatment on the affected tooth. In this instance, your dentist might recommend the internal bleaching of a root-filled tooth. This process involves drilling a small hole at the back of the tooth, removing, some of the filling from the root canal of the tooth, and inserting of the bleaching agent. The hole is then patched up with a temporary filling, and the bleaching agent plus the temporary filling will be removed in about one week’s time after insertion. This internal bleaching process may have to be repeated again to be able to adequately whiten the tooth. Your dentist may also suggest both internal and external bleaching depending on the state of your root canal tooth. Other options to this internal bleaching include veneers and crowns which are effective methods to achieve similar results.

The second reason for a single dark tooth is pulp degeneration. Such pulp degeneration is caused by either trauma to the tooth that causes the discolouration of the tooth (usually dark or reddish) or minor trauma that results in the deposition of secondary and tertiary dentin in the pulp (tooth will appear more yellowish). Whitening treatment of a single dark tooth is, therefore, more complex and may require veneer or crowns to cover up the colour. Your dentist may be able to recommend a successful and safe tooth whitening procedure that does not remove any of your tooth structure. Therefore in the case of a single dark tooth, please consult with your dentist who will be able to recommend an effective treatment. 

Treatment of teeth that have blue or grey discolourations.

Such blue or grey discolourations typically respond less well to tooth whitening procedures and as a result, require a longer treatment time. The cause of such discolouration may be due to antibiotics such as Tetracycline consumed when younger, causing a band of discolouration affecting many teeth. Thus, it is important that the patient’s expectations are moderated. Your dentist should be able to recommend a treatment plan that will lighten such discolourations and provide effective lightening treatment usually in combination with veneers or crowns to achieve a natural whitened result.

Tooth whitening only affects natural teeth and not restorations.

However, patients may see a slight whitening effect if there is discolouration around the anterior composite resin fillings because the whitening material is able to remove the discolouration. If the discrepancy of shade between the natural tooth and filling is too big, the restoration may need to be replaced after whitening to blend in. Teeth with laminate veneers are also whitened from the lingual side and appear whiter.

Over the counter tooth whitening kits versus professional whitening.teeth with whitening tray

Over the counter tooth whitening kits are cheaper than professional bleaching, however, unsupervised use of such kits may damage your teeth and gums. This is because some whitening kits contain strong chemicals that abrade the tooth enamel which also results in the patient developing tooth sensitivity with a thinned enamel layer. In the short term, the teeth may appear whiter, but in the long term, such prolonged damage of your teeth while using at-home whitening kits unsupervised might end up more costly to repair than professionally managed tooth whitening procedures.

Your treatment options are best discussed with your dentist.

Poor oral hygiene due to improper brushing or flossing habits, or certain medications can also contribute to teeth discolouration. Teeth may also discolour due to tooth decay, thin tooth enamel, tartar or calculus, and old fillings which can change the colour of the teeth to brown, grey or black. Excessive fluoride intake during early childhood may also stain and mottled teeth. Teeth that are discoloured due to staining or age see the best treatment results.

The dentist will be able to provide you with a comprehensive diagnosis and treatment plan for planning your smile treatment. The first step a dentist takes in your tooth whitening treatment plan is to carefully listen to you as to what you want to achieve with tooth whitening. It is important to tell your dentist the main cause of your tooth discolouration or staining due to lifestyle factors such as smoking, drinking coffee etc.

During your consultation, your dentist will perform a comprehensive intraoral examination with a tooth shade evaluation, followed by an analysis to complete your proper prognosis of the treatment outcome. You should also disclose to the dentist any previous tooth whitening treatments whether attempted at home or during previous dental visits. Other treatment options include composite resin bonding, porcelain laminates or all-ceramic crowns if bleaching is not able to achieve your desired whiteness. 


  1. Tooth Whitening: Facts and Fallacies
    H Heymann - (https://www.nature.com/articles/4812298)
  2. Us6783363b2 - Discolored Teeth Bleaching System
  3. In-office vital tooth bleaching--what do lights add?
  4. Three-Month Evaluation of Vital Tooth Bleaching Using Light Units—A Randomized Clinical Study
  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)