White & Shine!

  • November 2, 2021
  • 2 minutes read

Why do teeth lose their whiteness? As we age, the outer layer of the teeth’s enamel gets worn away, revealing the underlying dentin which is naturally yellow. However, tooth discoloration can also happen or be hastened because of the following reasons:

Food and drinks

Coffee, tea, cola and wine are notorious for staining teeth. The acidity in these beverages erodes the enamel of the teeth. Smoking and chewing tobacco also stains teeth because of the nicotine and tar in them (nicotine is colorless but turns yellow when oxidized). The extent of the discoloration also depends on how well we brush, floss and use mouthwash to remove plaque and stain-producers.

Diseases that affect enamel and tooth color

Enamel development in infants can be affected by infections during the mother’s pregnancy. Irradiation of the head and neck and chemotherapy can also cause teeth to discolor.


Antibiotics like tetracycline and doxycycline can discolor teeth that are still developing, like in children aged eight and below. Antihistamines like Benadryl, antipsychotic drugs and medication for high blood pressure can also discolor teeth. Even mouthwash containing chlorhexidine and cetylpyridinium chloride can stain teeth too!

Dental materials 

Dental amalgams—especially those containing silver sulfide—can turn teeth greyish.


Water containing high amounts of fluoride and excessive use of fluoride toothpaste and oral fluoride supplements can cause teeth to discolor.


Physical distress caused to teeth, such as damage by a fall, can disrupt proper enamel formation in children, whose teeth are still developing. Physical trauma can also cause internal discoloration in adult teeth, turning them blue or grey due to internal bleeding, as the blood leaks in through the dental nerves.

Teeth whitening options fall into 2 categories:

  1. Peroxide-containing bleaching agents
  2. Whitening toothpastes

Extrinsic stains: caused by food and drinks, smoking and poor hygiene; are best removed through routine scaling and polishing.

Intrinsic stains: caused by medication , fluoride and aging; can be treated with professionally prescribed teeth whitening procedures.

Category 1: Peroxide-containing Bleaching Agents

In-office teeth whitening by your dentist

This provides immediate results, with visibly whiter teeth after just one session. First, routine scaling and polishing will be done to maximise contact between teeth and the whitening gel. Then the dentist applies the whitening gel to the teeth and activates it with a light source.

Take-home teeth whitening kit from your dentist

Results are slower compared to in-office teeth whitening, with visible results only after a few weeks. During your first visit, the dentist will create dental impressions for customized trays for your teeth. On the second visit, you will receive the trays and syringes of bleaching gels. Depending on your teeth’s condition and the concentration of bleaching gel, bleaching duration usually lasts between 20 minutes and 2 hours daily.

Over-the-counter teeth whitening kits

Common forms include trays and strips that you place on your teeth. These are not prescribed by a dental professional so it would be wise to exercise caution while using these products. Using products with excessive hydrogen peroxide (H₂O₂) can damage teeth and gums, and cause sensitivity.

Should you venture into DIY whitening, ensure that the hydrogen levels in the products you choose are well within the Singapore Dental Association’s guidelines.

Category 2: Whitening Toothpastes

These contain polishing or chemical agents that remove surface stains through non-bleaching actions. Whitening toothpastes bought at retail outlets do not require a prescription; though they are unable to remove intrinsic stains.

Subscribe to the TQ Newsletter
For the latest healthcare and lifestyle offerings, subscribe to our newsletter