Enamel, which is one of the hardest parts of the entire body, is the outer part of a tooth. It is a highly mineralized tissue containing about 97% hydroxyapatite. The actual color of this pure hydroxyapatite is colorless or white, which ultimately gives the natural enamel a white color with some translucency. However, due to the continuous chemical and mechanical wear of enamel with increasing age and dietary habits, the enamel gets thinner and thinner, becoming more translucent, leading to the appearance of dentin. As a result, the overall tooth color will become darker.

Causes of tooth discoloration:

1.  Intrinsic staining: Genetics, age, fluorosis, and developmental disorders, certain medications and  heavy dental restorations; Non-vitality , trauma can cause tooth discoloration.

2. Extrinsic staining: Daily intake of   beverages like tea, coffee, smoking,pigments in beverages and foods, coloured tooth pastes, chewing tobacco, etc

Precautions:

1. Avoid colored beverages or foods on a daily basis.

2. Always rinse your mouth thoroughly after taking any colored beverages, such as tea, coffee, etc.

3. Try to use a straw to drink colored beverages; this would reduce the amount of contact area.

4. Avoid smoking and tobacco/pan chewing.

5. Do not brush aggressively with a colored and coarser tooth paste.

Treatment of teeth discoloration:

1.    Teeth whitening (i.e., bleaching)

2.    Veneers 

3.    Fixed ceramic or zirconia crown

4.    Teeth-colored restoration  

Teeth whitening is one of the most commonly requested treatments by the public. Though this is the most conservative approach to others, it is coded with its own pros and cons. Most teeth-whitening products or treatments are based on the active ingredient hydrogen peroxide (H₂O₂). Hydrogen peroxide reacts with double chromogen bonds, making the chromogen a lighter compound.

Various teeth whitening systems are available on the market; the selection of a product depends on the severity of teeth discoloration, apart from other attributes. 

The American Academy of Cosmetic Dentistry put forth the following approaches for teeth whitening:

1.    Whitening Toothpastes

2.    OTC Whitening Strips and Gels

3.    Whitening Rinses

4.    Tray-Based Tooth Whiteners

5.    In-Office Whitening

More severe or complex stains are best lightened professionally through in-office whitening, while over-the-counter products can be used for milder cases.

In-office whitening: In-office whitening will have better results compared to other treatment lines as the products deliver higher concentrations of peroxide than OTC, and usually gingival tissues are well protected. Some products claim to increase the rate of chromogen oxidation by exposure to heat or an intense blue light. In the present scenario, many dental professionals use laser systems to increase the rate of chemical reactions.

A recent systematic review by da Rosa et al. (2020) revealed that though tooth sensitivity with teeth whitening strips is less compared to dentist-supervised in-office bleaching, the latter led to a better color change than the whitening strips. 

Risks of teeth whitening:

1.     Increased tooth sensitivity 

2.     Mild gingival irritation

3.     Tooth erosion, 

4.     Tooth mineral degradation, 

5.     Increased susceptibility to demineralization and

6.     Pulpal damage

Tooth sensitivity is one of the common risks and adverse effects associated with bleaching vital teeth. The risks are dependent on intensity of the bleach and duration, severe sensitivity will sometimes pose risk to vitality of the teeth; and teeth whitening is usually recommended only under severe conditions where patients are highly aesthetically concerned or have developmental disputes.

Tooth whitening has become a recent trend amongst the general public as they demand whiter teeth for a happy social smile. With the advancements in dental materials, achieving this is possible with less invasive procedures like bleaching, resin infiltration, and veneers when compared to traditional full crowns, said Dr. Akshay V Anand, an endodontist in Bangalore, India.

With improving technology, there are always new products coming up for teeth whitening. It's not always wise to fall prey to advertising companies. Always consult the dentist before you choose any product for teeth whitening.

(Author: Dr. Meghana Pasala)