Ask Dr. Spiller
Does bleaching the teeth really work? In a
word, YES! It has been done in one form or another for the last 100 years,
and it has proven itself to be safe and effective. The current popularity
of the bleaching process goes back only about 10 years, catching on with the
public fairly quickly, and with dentists much more slowly over that time.
The reasons that dentists have been less quick to endorse the process are very
interesting, and not what you would expect. I will cover this aspect later
in this piece, but first, you need to know a bit more about the process itself.
Exactly what gets bleached during the
bleaching process?
The diagram to the right shows the internal
structure of a natural tooth. The layer you can see directly in the mouth
is the enamel layer which is the only portion of the tooth that should lie above
the gums. The natural color of enamel is white, but it is translucent and
the color of the other structures that underlie it tend to show through.
The material immediately under the enamel is called dentin. It's normal
color is yellow, but its structure is porous, and materials from the nerve
can permeate it causing it to darken to a brownish yellow as we get older.
The color we see when we look at a tooth in the mouth is a composite of the
colors of the enamel which may permanently stain as we get older, and the
underlying dentin which darkens over the years due to its close association with
the underlying nerve.
This is the reason that simply brushing the teeth
will not prevent the teeth from becoming darker yellow as we get older.
You can brush all day, but you will not be able to brush away the natural
internal color scheme.
Enter bleach! Root
canal treated teeth tend to be dark because the dead nerve which prompted
the root canal treatment turns a chocolate brown and permeates the surrounding
dentin before the dead material is removed during the root canal procedure.
It was discovered about 100 years ago that these teeth could be lightened up
substantially by temporarily sealing up a cotton pellet soaked with oxalic acid
inside the access hole in the crown of the root canal treated tooth. The
cotton pellet was removed after several days and the access was sealed with a
filling. Hydrogen peroxide may have been used to lighten teeth as early as
1884. In 1917, the process was speeded up using hydrogen peroxide and a
heat lamp. This is still the basic procedure used in some offices today.
Later, it was discovered that even dark vital
teeth (teeth with live nerves) could be bleached by soaking the tooth in 30%
hydrogen peroxide. This stuff is 10 times more concentrated than the type
you can buy in the drugstore, and in order to use it safely, the dentist had to
isolate the dark tooth with a rubber
dam. The peroxide could penetrate through the enamel into the dentin
and bleach out the dark color.
Finally, about 20 years ago, it was discovered
that a 10-percent carbamide peroxide solution could be applied to the
teeth safely without fear of burning or otherwise damaging the mouth, or
poisoning the patient. This dilute solution of peroxide, if kept in
contact with the teeth long enough bleached the teeth to a brighter color.
The longer the contact, the brighter the teeth got (up to a point.....sooner or
later, there's no color left to bleach out.).
Is bleaching safe?
8 out of 10 dentists now offer bleaching as an
esthetic treatment for their patients. The American Dental Association has
published the following statement:
"Dentist-prescribed, home-applied bleaching
made by a reputable manufacturer and used under the supervision of a dentist in
a relatively short-term treatment duration is safe and recognized as most
effective in lightening the color of teeth. Bleaching materials that have
received the ADA Seal of Acceptance are recommended.
Mild thermal sensitivity [sensitivity to cold] is
a common side effect associated with most in-office and dentist-prescribed home
bleaching methods. However, no long term irreversible tissue effects have been
demonstrated in relevant clinical studies."
Peer reviewed studies have found no irreversible
side effects from bleaching with 10 % carbamide peroxide.
Tooth Sensitivity
Bleaching solutions do cause your teeth to become
temporarily sensitive. In order to permanently bleach the teeth, the
solution must penetrate through the enamel to reach the underlying dentin.
(Click here
to see a schematic diagram of the anatomy inside a tooth.) The dentin
contains microscopic tubules which allow the flow of cellular fluids between the
living nerve in the center of the tooth and the outer layer of enamel.
This is the reason that the teeth become sensitive. It would be logical to
assume that this process can't be too good for the health of the nerve, however,
over the course of the years that these bleaching products have been used, no
ill effects have been reported. The sensitivity goes away within a few
days of terminating the bleaching treatments, and the nerves in the teeth suffer
no permanent damage. The sensitivity, while temporary, in rare cases may
be severe and has been known to force some patients to terminate the bleaching
treatment early.
What bleaching can't do
-
Bleaching will not bleach out the
black, brown or white color imparted to teeth due to decay.
Teeth should be repaired before bleaching is performed.
-
Bleaching will not bleach out darkness
imparted to teeth by old amalgam fillings. Removing the old
metal filling and replacing it with a new composite will usually accomplish
this, but if the tarnish has penetrated deeply into the tooth structure, the
tooth may remain permanently discolored.
-
Bleaching will not generally improve
the appearance of fluorosis
if the patient grew up in a part of the country (before the 1960's) that had
a high concentration of fluoride in the drinking water. This problem
is also prevalent in patients who "ate" a lot of fluoride
toothpaste when they were toddlers.
-
Bleaching is ineffective in reducing
the irregular gray horizontal lines seen on patients with tetracycline
stain in their tooth structure. Tetracycline stain is seen
primarily in older patients who received tetracycline to treat ear
infections when they were infants and toddlers. Physicians in those
days did not know that this drug would incorporate itself into the
developing teeth of children causing this deformity.
The different forms of dental bleaching
-
Whitening toothpastes: These are
over-the-counter preparations that have a low concentration of carbamide
peroxide. These toothpastes will work to brighten your teeth if you
are a very good
brusher, brush many times a day, and have a lot of patience. In
the years since these toothpastes have been on the market, I have seen only
one person who achieved real results using whitening toothpaste only.
They are very useful, however in maintaining the whitening achieved by using
trays and strips.
-
High concentration bleach in custom made
trays: This is the type of system that you can get at the
dentist's office. The bleaching material can only be bought with a
prescription and must be applied using the custom trays that the dentist or
his hygienist makes for you. Because of the high concentration of the
agent, and the close approximation with the teeth made possible by the
trays, this system produces very good results in anywhere from several hours
to several weeks of regular use. The agents have been improved and
strengthened over the years, and now the process is fairly easy. The main
disadvantage to using trays is that the teeth can become fairly sensitive
during treatment. This may be due more to the pressure applied to the
teeth by the trays than to the reaction of the nerves of the teeth to the
chemistry of the agent. In either case, the sensitivity vanishes once
the trays are no longer in use.
-
Bleach releasing disposable strips:
These are something new on the market, and there has not yet been enough
experience with them to evaluate their effectiveness. They are strips
of plastic with an adhesive on one side that allows them to adhere to the
teeth. They are applied and worn for several hours like the trays
described above. The main advantages to the strips is that no
impressions need to be taken to make trays, and the strips do not apply
pressure to the teeth causing the sensitivity that the tray applications are
famous for. A number of my patients have tried them. Some
have had good results. Others have had little or no improvement.
The inconsistency in results probably revolves around patient specific
factors such as manual dexterity, improper usage and varying oral chemistry.
-
In-office bleaching (Power bleaching): Some
offices offer a quick start bleaching procedure in which a concentrated
peroxide gel is placed on the teeth and allowed to remain in place while
heated with a lamp or a laser. Treatments like this tend to be faster,
but they require a lot of chair time which means that they are likely to be
expensive. Prior to the introduction of at-home tray-bleaching
techniques, this was the only form of bleaching offered to the public.
The tray method can achieve the same or better results, (albeit over a
greater length of time) with the added benefit of total patient control of
the degree of bleaching desired. They can use the trays as long
as they want, and keep them around for touch-ups later.
How we make bleaching trays in the office
The first step in bleaching involves a thorough
examination, X-rays and cleaning. Bleaching diseased teeth is like painting
a rusted out old car. The owner walks away thinking he has a new car, but
finds out soon that he is no better off than before. It is not ethical for
a dentist to perform an esthetic procedure like bleaching in the presence of
curable disease!
It is important to be aware that fillings,
including white fillings in the front teeth do not whiten with bleach.
Therefore, if you have any
composite fillings in your front teeth, they may have to be replaced
after the bleaching process since the shade of these fillings was chosen to
match the teeth as they were before bleaching. In practice, this is
not always necessary.
The second step is taking impressions of
the upper and lower teeth so models can be made to fabricate the bleaching
trays. The major problem with impressions is that people who gag may have
a difficult time. The key to having impressions taken is to be sure to
breath only through your nose. If you breath through your mouth during
this procedure, you will have gagging problems. I usually tell my patients
to practice by opening their mouths wide, and humming, being sure that
all the sound is coming out of their nose. When performing this feat, the
back of the tongue blocks off the throat, and since the impression material
cannot go any further down the throat than that, the gagging reflex is
suppressed. (This is really the same thing that happens when you are
chewing food which is why gaggers generally have no problems eating. You
will notice that when chewing food, you can hum at the same time.)
Finally, you get your trays and the bleaching
kit, and go home and begin the process. The instructions vary slightly
according to the type and manufacturer of the bleaching kit, but you generally
wear the trays anywhere from several hours several times a day, to overnight for
as long as you want to keep the process up.
Are "over-the-counter" bleaching
methods as good as the kind you get from the dentist?
Even though the concentration of the bleach
available from sources such as the Home Shopping Network continues to increase
until it nearly reaches the strength available from your dentist, the results
you can expect from all of the over-the-counter methods are never as good as you
can get with prescription dental bleaching methods. The reason for this is
that the dentist can provide custom bleaching trays that fit your teeth
tightly and keep the bleach in undiluted contact with the teeth for long periods
of time. Neither bleaching strips nor the stock trays provided
in the over-the-counter bleaching systems can do this.
The advantage to the availability of the dental
bleaching agents through sources such as the home shopping network is that once
you finish a prescription bleaching regime, your custom trays remain in your
possession indefinitely, and touchups, or continued bleaching can be done using
the prescription custom trays and the relatively less expensive bleaching agents
available from commercial sources.
So why did it take dentists so long to come
around?
In order to answer this question, it is helpful
to begin by reading my page on the Nature
of dental practices. In fact, most dentists are not just out to make a
fast buck. If that were the case, there would have been no hesitation in
the acceptance of bleaching by individual dentists.
A substantial majority of general dentists are
what I call the "dentists in the trenches". Although we all do
esthetic work, the majority of our time is spent alleviating pain, curing
infections, saving bombed out teeth, teaching oral hygiene and generally making
our patients feel better about their mouths, and themselves. You could say
that we are really physicians who specialize in the mouth.
For me, and I suspect for a lot of the other
older guys who have been practicing dentistry in the trenches for so many years,
it was hard to work bleaching into our concept of what dentistry means. We
see dentistry as a branch of health care, but bleaching teeth seems to fall more
under the rubric of cosmetology. It seems more akin to dying your hair, or
applying fingernail polish. Thus, when it first became apparent that there
was a market for whitening teeth, many of us were reluctant to integrate it into
our concept of the meaning of what we do for a living. "Teeth are supposed
to be off-white, and they are supposed to get darker with age.
It's normal!" And normality is what health is all about.
What changed my mind was my hygienist, Jen.
She is, in fact, an esthetician who specializes in skin care. That's what
she did before she became a hygienist. (Note that teeth are
"dermal" structures, so she's really still in her field.) She
really really wanted to bleach teeth. So I bought the kits and let her
have at it. The first thing that struck me was how well it worked. I
had no problems telling who had bleached their teeth and who hadn't. The
second thing that absolutely amazed me was the sheer number of patients who
wanted to have it done. People who I had been treating for years and who
it never occurred to me would want to bleach their teeth were showing up with
teeth that fluoresced in the dark. And they were very very happy.
So I realized that bleaching does fit into
the general concept of health.....mental health! When a person looks in a
mirror and likes what he sees, he feels better all over.
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