Teeth whitening is the most popular dental services
provided. For Men and women alike, your smile is
important. It's one of the first things people notice.
Teeth whitening can make those moments even more
impressionable. It is the perfect time to feel better
about you smile.
Why
do my teeth have stains and discolorations?
Most stains are caused by age, tobacco, coffee,
or tea. Other types of stains can be caused by antibiotics,
such as tetracycline; or too much fluoride.
Tooth
bleaching, also known as tooth whitening, is a common
procedure in general dentistry but most especially
in the field of cosmetic dentistry. Many people
consider white teeth to be an attractive feature
of a smile. A child's deciduous teeth are generally
whiter than the adult teeth that follow. As a person
ages the adult teeth often become darker due to
changes in the mineral structure of the tooth, as
the enamel becomes less porous. Teeth can also become
stained by bacterial pigments, foodstuffs and tobacco.
The
procedure to bleach teeth uses oxidizing agents
such as hydrogen peroxide or carbamide peroxide
to lighten the shade of the tooth. The oxidizing
agent penetrates the porosities in the rod-like
crystal structure of enamel and oxidizes interprismatic
stain deposits; over a period of time, the dentin
layer, lying underneath the enamel, is also bleached.
The effects of bleaching can last for several months,
but may be shortened by cigarette smoking, and tea
and coffee consumption.
Methods
There are two main methods of bleaching--one performed
by a dentist and one self-performed. A dentist applies
a high concentration of oxidizing agent for a short
period of time, which produces quick results. In
order to reduce the risk of chemical burns to the
soft tissues, most in-office bleaching procedures
use a light-cured protective layer that is carefully
painted on the gums and papilla (the tips of the
gums between the teeth). The bleaching agent is
either carbamide peroxide, which breaks down in
the mouth to form hydrogen peroxide, or hydrogen
peroxide itself. The bleaching gel typically contains
up to 35% carbamide peroxide which is roughly equivalent
to a 12% hydrogen peroxide concentration.
At-home
whitening involves purchasing a thin mouthguard
or strip that holds a relatively low concentration
of oxidizing agent next to the teeth for as long
as several hours a day for a period of 5 to 14 days.
This is known as take-home or over-the-counter bleaching.
Results can vary, depending on which application
is chosen, with some people achieving whiter teeth
in a few days, and others seeing very little results
or no results at all. Whitening is potentially better
at a dentist because the strip or mouth-guard does
not completely conform to the shape of the teeth,
sometimes leaving the tips of the teeth (near the
gumline) unbleached. The bleaching agent is typically
less than 10% hydrogen peroxide equivalent so irritation
to the soft tissue around teeth is minimized. Dentists
as well as some dental laboratories can fabricate
custom fitted whitening trays that will greatly
improve the results you can achieve with an "at
home" whitening method.
A
typical course of bleaching can produce dramatic
improvements in the cosmetic appearance of most
stained teeth; however, some stains do not respond
to bleaching. Tetracycline staining may require
prolonged bleaching, as it takes longer for the
bleach to reach the dentine layer. White-spot decalcifications
may also be highlighted and become more noticeable.
Bleaching is least effective if teeth have white
spots, decay or infected gums. It is also least
effective when the original tooth color is grayish.
Bleaching is most effective with yellow discolored
teeth.
Recently,
efforts have been made to accelerate the bleaching
process by the use of light. Studies have shown
varying results as to the efficacy of light-activated
bleaching.
Risks
Side effects of tooth bleaching include: chemical
burns (if a high-concentration oxidizing agent contacts
unprotected tissues, which may bleach or discolor
mucous membranes), sensitive teeth, and overbleaching
(known in the profession as "over white teeth").
Rebound, or teeth losing the bleached effect and
darkening, is also an issue, with some studies showing
the rebound effect over 30 days. A recent study
by Kugel et al has shown that as much as 4 shades
of lightness can be lost over 30 days with light-activated/office
bleaching.
The
two side effects that occur most often are a temporary
increase in tooth sensitivity and mild irritation
of the soft tissues of the mouth, particularly the
gums. Tooth sensitivity often occurs during early
stages of the bleaching treatment. Tissue irritation
most commonly results from an ill-fitting mouthpiece
tray rather than the tooth-bleaching agent. Both
of these conditions usually are temporary and disappear
within 1 to 3 days of stopping or completing treatment.
Individuals
with sensitive teeth and gums, receding gums and/or
defective restorations should consult with their
dentist prior to using a tooth whitening system.
Anyone allergic to peroxide (the whitening agent)
should not use a bleaching product. Also, prolonged
exposure to bleaching agents may damage tooth enamel.
This is especially the case with home remedy whitening
products that contain fruit acids.
Bleaching
is not recommended in children under the age of
16. This is because the pulp chamber, or nerve of
the tooth, is enlarged until this age. Tooth whitening
under this condition could irritate the pulp or
cause it to become sensitive. Tooth whitening is
also not recommended in pregnant or lactating women.
Tooth
whitening does not usually change the colour of
fillings and other restorative materials. It does
not affect porcelain, other ceramics, or dental
gold. However, it can slightly affect restorations
made with composite materials, cements and dental
amalgams. Tooth whitening can restore colour of
fillings, porcelain, and other ceramics when they
become stained by foods, drinks, and smoking, amongst
other activities.
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 — tycally 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.
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 the only 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.
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.
In-Office
Teeth Whitening
Professional
in-office teeth whitening is the most popular cosmetic
dental procedure in the world today. Unlike home-use
whitening systems that incorporate low-dose bleaching
agents, in-office whitening (also known as power
bleaching, power whitening, professional whitening
or chairside whitening) takes place under carefully
monitored conditions which allow for the safe, controlled,
pain-free use of a relatively high concentration
of bleaching gel — yielding results that are visible
immediately.
Advantages
of In-Office Whitening
*
No other teeth whitening procedure produces faster
results.
* This is the safest form of tooth bleaching.
* Gum and tooth sensitivity (formerly drawbacks
to in-office bleaching) are more controllable today
due to thicker peroxide gels (that don’t soak into
the teeth as much as previous gels) and the use
of desensitizers such as potassium nitrate and fluoride.
Disadvantages
of In-Office Whitening
*
In-office bleaching is more expensive than take-home
alternatives. Its cost, on average, is $650, compared
to $400 for take-home trays and under $100 for over-the-counter
bleaching trays or whitening strips.
* Results can be unpredictable, depending on factors
such as age, heredity and the type of staining that
is present.
* In-office bleaching is not a permanent solution.
Shortly after treatment is completed, the teeth
resume accumulating stains. Many dentists therefore
recommend home maintenance follow-up with a lower-percentage
bleach that can be kept on the teeth for longer
periods of time.
Stains
That are Best Removed with In-Office Whitening
Chairside
whitening removes organic stains or discolorations
primarily caused by:
*
Aging. Over time, the teeth darken with a yellow,
brown, green or grey cast (which may be due to heredity
and/or eating habits). Yellowed teeth tend to whiten
most readily.
* Consumption of certain foods (notably coffee,
red wine, sodas and dark-colored vegetables and
fruits).
* Tobacco use.
Stains
Resistant to In-Office Whitening
*
Teeth with certain stains — typically those that
are inorganic — do not respond well to in-office
whitening. In fact,
these teeth may look even darker after the surrounding
teeth have been whitened.
* Trauma, which causes the dentin to darken.
* Tetracycline antibiotics ingested during tooth-formation.
These drugs chemically bind with the crystalline
structure of both the tooth’s enamel and underlying
dentin.
* Overexposure to fluoride, which can cause fluorosis,
resulting in tooth discoloration.
The
In-Office Teeth Whitening Procedure
Typically, the steps involved are not painful or
uncomfortable; in fact, many patients doze or watch
a DVD or TV during the procedure.
* A cheek retractor is inserted into the mouth,
exposing all the “esthetic zone” teeth (teeth that
are visible when you smile).
*
A liquid rubber dam or hardening resin is painted
onto the gum tissue to protect against any irritation
caused by the bleaching gel.
*
A bleaching gel containing hydrogen peroxide is
applied to the esthetic zone teeth and kept on for
approximately 15 to 30 minutes.
*
The bleaching gel is suctioned or washed off, and
fresh gel is applied for one or more additional
periods of 15 to 30 minutes. The ultraviolet light
is designed to enhance the in-office bleaching process.
*
Some whitening treatments incorporate an intense
light that is focused on the teeth and is said to
activate or enhance the bleaching process. Opinions
vary as to whether this light improves the bleaching
outcome.
*
Between gel applications, the teeth are checked
to see how well they have whitened, and whether
more bleach needs to be applied.
*
After the final gel application, the cheek retractors
are removed, the patient rinses and the immediate
post-treatment shade change is measured. The teeth
may whiten by as few as two to three shades or as
many as eight (out of a total of 16). Part of the
whitening effect is due to dehydration during the
bleaching process, which makes the teeth look whiter
than their true new color. That color will emerge
after a couple of days.
If
a satisfactory level of whitening hasn’t been achieved,
your dentist may recommend follow-up in-office bleaching
at a future date, and/or a regimen of take-home
bleaching trays.
