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Adriana Manso, a clinical assistant professor in the
Faculty of Dentistry, explains how whitening and
bleaching products work and why we have to be
careful if we are considering using them.
What are your concerns about dental bleaching
products?
Bleaching products can have multiple side effects
such as damaging the dental enamel, causing
irritation to the gums, tooth sensitivity and more.
Some of these effects are lasting; for example the
damage to the dental enamel is permanent and
irreversible. There is also an obvious risk of
overuse or abuse when applying over-the-counter
bleaching products such as strips, paint-ons or
trays. Nowadays, with so many over-the-counter
bleaching alternatives available, people are tempted
to buy and self-apply these products without
properly understand the risks.
It is important to remember that dental bleaching is
not recommended for everyone. I would always advise
discussing bleaching with your dentist first. There
are different reasons why a person’s teeth are
discoloured or darker so the treatment options and
results would also differ.
How does bleaching your teeth work?
Bleaching products contain hydrogen peroxide that
diffuses through the enamel. It breaks down the
compounds that are causing the discolouration, known
as chromogenic compounds, and your teeth become
lighter. Over-the-counter products like strips or
gels usually contain lower concentration of hydrogen
peroxide than bleaching products used only by
dentists.
Bleaching products used by the dentist for in-office
therapies can have higher peroxide concentrations of
up to 40 per cent. The bleaching mechanism is
similar but these therapies need to be well
supervised and should only be used in the dentist’s
office. Alternatively, dentists can prescribe
supervised at-home bleaching therapies.
Some toothpastes and floss claim to whiten teeth and
they work differently than bleaching products. They
contain abrasives or tiny particles that work like
sandpaper to exfoliate the surface of the tooth and
remove the stains. This whitening process has a side
effect too. If you use toothpaste that is too
abrasive for a long time, you can remove superficial
layers of your enamel.
How can you tell if you’re overdoing the
bleaching?
There is a limit to how much you can bleach your
teeth; the process will plateau and the peroxide
doesn’t cause any further whitening. Instead, it
breaks down the proteins of the enamel and alters
its structure. Dentists use shade guides to verify
the progress of the bleaching based on the patient’s
initial shade and can determined when the bleaching
reached the plateau. There are reports of
significant enamel damage associated with
over-the-counter bleaching products, most likely due
to unassisted over bleaching.
Tooth sensitivity — meaning patients feel pain when
they consume hot or cold drinks or food — is the
most noticeable side effect of bleaching. It can be
caused by multiple factors such as peroxide
concentration, application time, and the presence of
defective restorations and cracks or cavities. It is
important to highlight that high sensitivity is not
a good sign and the pain is your ‘red flag’ that
something is going beyond the limits.
How often can you use whitening products?
Bleaching should not be done every year because the
effects on your enamel are cumulative. People want
whiter teeth for their graduation, their wedding and
then their sister’s wedding and they do it year
after year.
When a patient wants whiter teeth they need to
consider whether they are willing to change their
habits. Smoking and drinking coffee, tea and red
wine are examples of habits that can cause
discolouration. It makes no sense to have your teeth
bleached if you are not willing to change your
habits that cause discolouration. This only creates
more demand for bleaching and leads to overuse of
bleaching products.
Young patients like teenagers or young adults are
more susceptible to the marketing for teeth
whitening. They want a bright smile and sometimes
they are not as concerned or aware about the side
effects. Over-the-counter options are appealing as
they are marketed as fast and low-cost alternatives
to the public. Unfortunately, young patients are
also the most susceptible to the side effects of
bleaching products as their teeth are more
permeable.
See also
Fast toothpaste check (02/10/2012)
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For more information
The University of British Columbia
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MDN |