DENTAL
PROCEDURES Teeth Whitening
In the world of cosmetic dentistry, teeth whitening reigns supreme. Universally
valued by men
and women alike, whitening (or bleaching) treatments are available to satisfy
every budget,
time frame and temperament.
Whether in
the form of one-hour bleaching sessions at your dentist’s office, or home-use
bleaching kits purchased at your local drugstore, teeth whitening solutions
abound. Yet
only 15 percent of the population has tried the cosmetic procedure, and
misinformation
on the subject is rife.
The long
and the short of it is that teeth whitening works. Virtually everyone who opts
for
this cosmetic treatment will see moderate to substantial improvement in the
brightness
and whiteness of their smile. However, teeth whitening is not a permanent
solution and
requires maintenance or "touch-ups" for a prolonged effect.
Bleaching
vs. Whitening
According
to the FDA, the term "bleaching" is permitted to be used only when
the teeth
can be whitened beyond their natural color. This applies strictly to products
that contain
bleach — typically hydrogen peroxide or carbamide peroxide.
The term
"whitening," on the other hand, refers to restoring a tooth’s surface
color by
removing dirt and debris. So any product that cleans (like a toothpaste) is
considered
a whitener. Of course, the term whitening sounds better than bleaching, so it
is
more frequently used — even when describing products that contain bleach.
Why
Teeth Whitening? Examining Enamel
Most of
us start out with sparkling white teeth, thanks to their
porcelain-like enamel
surface. Composed of microscopic crystalline rods, tooth enamel is designed to
protect
the teeth from the effects of chewing, gnashing, trauma and acid attacks
caused by sugar.
But over the years enamel is worn down, becoming more transparent and
permitting
the yellow color of dentin — the tooth’s core material — to show through.
During
routine chewing, dentin remains intact while millions of micro-cracks occur in
the
enamel. It is these cracks, as well as the spaces between the crystalline
enamel
rods, that gradually fill up with stains and debris. As a result, the teeth
eventually develop
a dull, lackluster appearance.
Teeth
whitening removes the stains and debris, leaving the enamel cracks open and
exposed. Some of the cracks are quickly re-mineralized by saliva, while others
are filled
up again with organic debris.
Tooth
Discoloration: The Two Types of Tooth Stains
There
are two categories of staining as it relates to the teeth: extrinsic staining
and
intrinsic staining.
Extrinsic
stains are those that appear on the surface of the teeth as a result of
exposure to
dark-colored beverages, foods and tobacco, and routine wear and tear.
Superficial extrinsic
stains are minor and can be removed with brushing and prophylactic dental
cleaning.
Stubborn extrinsic stains can be removed with more involved efforts, like teeth
bleaching. Persistent extrinsic stains can penetrate into the dentin and become
ingrained
if they are not dealt with early.
Intrinsic
stains are those that form on the interior of teeth. Intrinsic stains result
from trauma,
aging, exposure to minerals (like tetracycline) during tooth formation and/or
excessive
ingestion of fluoride. In the past, it was thought that intrinsic stains were
too resistant
to be corrected by bleaching. Today, cosmetic dentistry experts believe that
even
deep-set intrinsic stains can be removed with supervised take-home teeth
whitening
that is maintained over a matter of months or even a year.
What
Causes Tooth Staining?
Age: There
is a direct correlation between tooth color and age. Over the years, teeth
darken
as a result of wear and tear and stain accumulation. Teenagers will likely
experience
immediate, dramatic results from whitening. In the twenties, as the teeth begin
to show
a yellow cast, teeth-whitening may require a little more effort. By the
forties, the yellow gives
way to brown and more maintenance may be called for. By the fifties, the teeth
have
absorbed a host of stubborn stains which can prove difficult (but not
impossible) to remove.
Starting
color: We are all equipped with an inborn tooth color that ranges from
yellow-
brownish to greenish-grey, and intensifies over time. Yellow-brown is generally
more
responsive to bleaching than green-grey.
Translucency
and thinness: These are also genetic traits that become more pronounced
with age. While all teeth show some translucency, those that are opaque and
thick
have an advantage: they appear lighter in color, show more sparkle and are
responsive to bleaching. Teeth that are thinner and more transparent — most
notably the front teeth — have less of the pigment that is necessary for
bleaching.
According to cosmetic dentists, transparency is theonly condition that cannot
be corrected
by any form of teeth whitening.
Eating
habits: The habitual consumption of red wine, coffee, tea, cola,
carrots, oranges
and other deeply-colored beverages and foods causes considerable staining over
the
years. In addition, acidic foods such as citrus fruits and vinegar contribute
to enamel erosion.
As a result, the surface becomes more transparent and more of the
yellow-colored dentin
shows through.
Smoking
habits: Nicotine leaves brownish deposits which slowly soak into the
tooth
structure and cause intrinsic discoloration.
Drugs /
chemicals: Tetracycline usage during tooth formation produces dark grey or
brown ribbon stains which are very difficult to remove. Excessive consumption
of
fluoride causes fluorosis and associated areas of white mottling.
Grinding: Most
frequently caused by stress, teeth grinding (gnashing, bruxing, etc.) can
add to micro-cracking in the teeth and can cause the biting edges to darken.
Trauma: Falls
and other injuries can produce sizable cracks in the teeth, which
collect large amounts of stains and debris.
Teeth
Whitening options
Three
major teeth whitening options are available today. All three rely on varying
concentrations of peroxide and varying application times.
In-Office
Whitening
Significant
color change in a short period of time is the major benefit of in-office
whitening.
This protocol involves the carefully controlled use of a relatively
high-concentration peroxide
gel, applied to the teeth by the dentist or trained technician after the gums
have been
protected with a paint-on rubber dam. Generally, the peroxide remains on the
teeth for
several 15 to 20 minute intervals that add up to an hour (at most). Those with
particularly
stubborn staining may be advised to return for one or more additional bleaching
sessions,
or may be asked to continue with a home-use whitening system.
Cost: $
per visit (on average) nationwide.
Professionally
Dispensed Take-Home Whitening Kits
Many dentists are of the opinion that professionally dispensed take-home
whitening
kits can produce the best results over the long haul. Take-home kits
incorporate an
easy-to-use lower-concentration peroxide gel that remains on the teeth for an
hour
or longer (sometimes overnight). The lower the peroxide percentage, the
longer it may
safely remain on the teeth.
The gel is applied to the teeth using custom-made bleaching trays that resemble
mouth
guards.
Cost: $
to $.
Over-the-Counter
Whitening
The
cheapest and most convenient of the teeth whitening options, over-the-counter
bleaching involves the use of a store-bought whitening kit, featuring a
bleaching
gel with a concentration lower than that of the professionally dispensed
take-home
whiteners. The gel is applied to the teeth via one-size-fits-all trays,
whitening strips
or paint-on applicators. In many cases this may only whiten a few of the front
teeth
unlike custom trays that can whiten the entire smile.
Cost: $
to $.
Hydrogen
Peroxide vs. Carbamide Peroxide
The
bleach preference for in-office whitening, where time is limited, is powerful
and
fast-acting hydrogen peroxide. When used in teeth bleaching, hydrogen peroxide
concentrations range from approximately nine percent to 40 percent.
By
contrast, the bleach of preference for at-home teeth whitening is slower acting
carbamide peroxide, which breaks down into hydrogen peroxide. Carbamide
peroxide
has about a third of the strength of hydrogen peroxide. This means that a
15 percent
solution of carbamide peroxide is the rough equivalent of a five percent
solution of
hydrogen peroxide.
How
White Can You Go? A Matter of Esthetics
Teeth
whitening results are subjective, varying considerably from person to person.
Many
are immediately delighted with their outcome, while others may be disappointed.
Before you
embark on any whitening treatment, ask your dentist for a realistic idea of the
results you are
likely to achieve and how long it should take to achieve them. Expectations
play a major role
in teeth whitening.
Shade guides help your dentist determine the most natural white for you.
Whitening
Shade Guides
In the
dental office, before-and-after tooth color is typically measured with shade
guides.
These are hand-held displays of wide ranges of tooth colors. (Dentists also use
them in
choosing crown and other restoration shades.)
The
standard-setter among them has long been the Vitapan Classic Shade Guide. This
shade guide standard incorporates 16 shades, systematically arranged from light
to dark
into four color groups, and provides a universal tooth-color terminology.
While
whitening can occasionally lighten tooth color by nine or more shades, most of
those
who bleach their teeth are likely to see a change of two to seven shades.
Teeth
Whitening Risks
Teeth
whitening treatments are considered to be safe when procedures are followed as
directed. However, there are certain risks associated with bleaching that you
should be
aware of:
Sensitivity:
Bleaching can cause a temporary increase in sensitivity to temperature,
pressure
and touch. This is likeliest to occur during in-office whitening, where
higher-concentration
bleach is used. Some individuals experience spontaneous shooting pains
(“zingers”) down
the middleof their front teeth.
Individuals at greatest risk for whitening sensitivity are those with gum
recession, significant
cracks in their teeth or leakage resulting from faulty restorations. It has
also been reported
that redheads, including those with no other risk factors, are at particular
risk for tooth
sensitivity and zingers.
Whitening
sensitivity lasts no longer than a day or two, but in some cases may persist up
to a month. Some dentists recommend a toothpaste containing potassium nitrate
for
sensitive teeth.
Gum
irritation: Over half of those who use peroxide whiteners experience some
degree of
gum irritation resulting from the bleach concentration or from contact with the
whitening trays.
Such irritation typically lasts up to several days, dissipating after bleaching
has stopped or
the peroxide concentration lowered.
Technicolor teeth:
Restorations such as bonding, dental crowns or porcelain veneers are
not affected by bleach and therefore maintain their default color while the
surrounding teeth
are whitened. This results in what is frequently called “technicolor teeth.”
Maintaining Your Whiter
Smile
To
extend the longevity of newly whitened teeth, dentists are likely to recommend:
At-home
follow-up or maintenance whitening — implemented immediately or performed
as infrequently as once a year.
Avoiding dark-colored foods and beverages for at least a week after whitening.
Whenever possible, sipping dark-colored beverages with a straw.
Practicing excellent oral hygiene — brushing and flossing after meals and at
bedtime.
Caveats
In
addition to the aforementioned risk factors, a number of caveats should be
considered
before undergoing teeth whitening:
No
amount of bleaching will yield “unnaturally” white teeth.
Whitening results are not fully seen until approximately two weeks after
bleaching. This is
an important consideration if you are about to have ceramic restorations and
want to be sure
the color matches that of your newly bleached teeth.
To avoid the technicolor effect, tooth-colored restorations will likely need
replacement
after bleaching.
Recessed gums often reveal their yellowish root surfaces at the gum line. That
yellow color
has proven difficult to bleach.
Pregnant or nursing women are advised to avoid teeth whitening. The potential
impact
of swallowed bleach on the fetus or baby is not yet known.
For more
information visit our FAQ
page.