How to Whiten Teeth: 10 Essential Facts You Must Know (2024)

Dental Designs Clinic Singapore
16 Feb, 2024

Ever wanted pearly whites like your favourite movie stars? Tooth whitening or bleaching can provide you with a bright and white smile that you can confidently show and make a great first impression. But how exactly does that happen? Here are 10 facts on teeth whitening.


1) How does teeth whitening work?

Tooth whitening uses bleaching agents, specifically carbamide peroxide and hydrogen peroxide, to lighten the colour of the teeth. Since our teeth are semi-permeable, these chemicals penetrate the tooth enamel to remove stains1. Additionally, when undergoing teeth whitening in a dental clinic, dentists often use special bleaching lights which catalyses the chemical process, thus accelerating the whitening process.


2) Why do i have stained/yellow teeth?

The colour of our teeth is determined by the layer of tooth enamel covering them. Teeth may be intrinsically discoloured as tooth enamel naturally comes in different shades varying from light yellow to off-white. Alternatively, 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. It is also natural for teeth to change color and become darker or more yellow as we age. In fact, teeth whitening is becoming a popular option among older individuals seeking a more youthful appearance.


3) will teeth whitening make my teeth sensitive?

In-office teeth whitening is a minimally invasive procedure and when performed by a qualified dentist, is both safe and painless. If it is your first or second treatment, you may experience some teeth sensitivity but this typically will subside with time and your dentist may recommend products with potassium nitrate and sodium fluoride gel to alleviate this temporary sensation of sensitivity.


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

The extent of whitening and brightening of the teeth is reliant on numerous factors, including the individual tooth condition, the cause of discolouration and how effectively the dentist’s post-procedural instructions were followed. 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.before-and-after-teeth-whitening

5) 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 such cases, your dentist may suggest internal bleaching, veneers or crowns. The second reason for a single dark tooth is pulp degeneration, often triggered by trauma to the tooth.

Teeth whitening treatment of a single dark tooth is, therefore, more complex and may require veneer or crowns to cover up the colour. It is always best to consult with your dentist who will be able to recommend an effective treatment. 


6) can i whiten 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 underlying cause of such discolouration may be due to antibiotics such as Tetracycline consumed when younger, which leads to a band of discolouration that affects many teeth. Accordingly, a combination of teeth whitening and veneers or crowns may be needed to achieve a natural whitened appearance.


7) in-office teeth whitening or take-home whitening kits, which is better for me?

In-office whitening offers you immediate results, revealing a smile of at least 2-4 shades whiter than your current teeth. The process utilises whitening gel that is activated by laser or light2 to accelerate the whitening process. Your lips and gums will be protected from the bleaching agent with rubber seals or gel that the dentist prepares beforehand. However if the starting shade is very dark, multiple sessions may be required to achieve enhanced whitening effect.

Home whitening kits, in contrast, deliver a more gradual whitening outcome. The dentist will take a mould of your teeth to make custom-fit trays. At home, you will be able to fill these trays with bleaching gels and wear them between an hour to overnight, depending on your dentist’s instructions. These gel-filled trays are needed to be worn for at least two to four weeks. This gradual process allows you to lighten tooth shades according to your preference.teeth-with-whitening-tray

8) do i need to avoid certain food after i whiten my teeth?

We would recommend avoiding certain foods and beverages immediately after teeth whitening. Those that can potentially stain or discolor your teeth or are likely to irritate your sensitive teeth should generally be avoided. These include dark coloured food and drinks, like coffee and tea, as well as acidic food and drinks such as citrus fruits and carbonated drinks. 


9) is teeth whitening permanent?

Teeth whitening is not permanent and factors such as lifestyle choices, dietary habits, and natural tooth discoloration can gradually diminish the whiteness achieved through whitening treatments. On average, both in-office and take-home teeth whitening treatments can maintain their effects for up to 3 years. However, it is recommended to go for periodic touch-ups to keep your smile bright and white.


10) Your treatment options are best discussed with your dentist!dentist-performing-in-office-whitening

Your dentist is still the best person to advise which whitening procedure will be most suitable for you! They will perform a comprehensive intraoral examination with a tooth shade evaluation, followed by an analysis to complete your proper prognosis of the treatment outcome. 

Ready to explore the world of teeth whitening? Book an appointment with us!



  1. Heymann HO. Tooth whitening: facts and fallacies. Br Dent J. 2005 Apr 23;198(8):514. doi: 10.1038/sj.bdj.4812298. PMID: 15849600.
  2. Luk K, Tam L, Hubert M. Effect of light energy on peroxide tooth bleaching. J Am Dent Assoc. 2004 Feb;135(2):194-201; quiz 228-9. doi: 10.14219/jada.archive.2004.0151. PMID: 15005435.