Written by: Dennis Kwan
Edited by Yinwa Yung
Nobody wants a beautiful smile with yellow stains on it. Minor touch-ups can extend the life of your smile by years or decades. There are numerous dental clinics around the world that offer low-cost teeth whitening treatments. If you are in good hands, the teeth whitening treatment can be very effective. It certainly depends on the dentist and his or her experience, but it also depends to some extent on you and how you care for your beautiful teeth after teeth whitening treatment.
Teeth whitening can benefit almost anyone, though it may not be as effective for some as it is for others. Teeth whitening is the most effective treatment for:
Stains caused by tobacco and long-term use of cigarettes
Stains from frequent consume of tea, coffee, or red wine
Stains caused by aging (particularly found in elderlies above 70 years of age)
So what is teeth whitening?
Teeth whitening is a simple procedure. The goal of teeth whitening and lightening is to remove yellow or discolored enamel from your teeth. Many people believe that tooth whitening is only used to remove stains, but this is not true. One of two tooth bleaches is used in whitening products (hydrogen peroxide or carbamide peroxide). Those bleaches break down stains into smaller, less noticeable components, leaving your teeth toneless and brighter.
Figure 1 & 2 shows the difference in results after bleaching. (Themes, 2015)
A redox reaction is the oxidation/reduction reaction that occurs during bleaching. In a redox reaction, the oxidising agent, hydrogen peroxide, releases free radicals with unpaired electrons and thus becomes reduced. The discolored molecules within the teeth accept the unpaired electrons and oxidize, causing the discoloration to fade.
Figure 3 shows the structural formula of carbamide peroxide. (Themes, 2015)
Hydrogen peroxide is an oxidizing agent that generates highly reactive free radicals HO2• and O•. The stronger and more reactive of the two free radicals is the perhydroxyl ion HO2•. The bleaching material must be alkaline in order for HO2• to be readily available. The ideal pH for releasing HO2• is around pH 10.
Figure 4 highlights the reactions taking place during bleaching. (Themes, 2015)
Dentists mix glycerin and xylose to make artificial whitening solutions. The liquid hydrocarbons glycerin and xylose are both liquid hydrocarbons. A higher glycerin concentration can improve the whitening solution's strength, durability, and shine.
Teeth whitening is done in one of two ways:
Tray Whitening:
The main components of this procedure are custom-made trays and whitening gel. The whitening gel is applied to the tray (which is custom-made to fit your teeth), and the tray is then placed over your teeth. The presence of hydroxyl radicals in the gel causes brown or yellow teeth to turn white. In 1-15 days, the teeth lighten in color.
Figure 5 illustrates how a tray whitening kit looks like. (Amazon.com, 2015)
Light-Activated Whitening System:
A bleaching powder is applied to your teeth, and then an elevated-power UV light is precisely positioned. This light aids in the whitening of the teeth. The results are extremely fast, with some people noticing results as soon as 45 minutes after the procedure.
Implications and risks of teeth whitening:
Gums acting sensitive to the chemicals and bleaching agents
Slight chances of burned gums and harm to tooth enamel
The outcome of whitening is unpredictable. Some people have a very light shade, while others have a darker shade. But, in the end, it comes down to how much intensity and concentration you can handle.
References:
Amazon.com : Custom Teeth Whitening Trays (Upper+Lower Set) : Tooth Whitening Products : Beauty & Personal Care. (2015). Amazon. https://www.amazon.com/Upper-Custom-Dental-Whitening-Bleaching/dp/B004EKVOU2
An Overview of Teeth Whitening. (2003, June 3). WebMD. https://www.webmd.com/oral-health/teeth-whitening
C. (2021, September 30). Teeth Whitening Trays: How they Work and Alternatives. Crest. https://crest.com/en-us/oral-care-tips/teeth-whitening/teeth-whitening-trays-how-they-work-alternatives
NHS website. (2021, November 18). Teeth whitening. Nhs.Uk. https://www.nhs.uk/live-well/healthy-body/teeth-whitening/
Themes, U. (2015, January 3). 1: Chemistry and Safety of Dental Bleaching. Pocket Dentistry. https://pocketdentistry.com/1-chemistry-and-safety-of-dental-bleaching/
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