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Wisdom teeth (and
why they should be removed)
 Wisdom teeth are known as third molars in dentistry. In
the X-ray film above, if you count the number of large teeth from the front of
the mouth to the back, you can see that the "third" ones are impacted
(as defined above). They are called wisdom teeth because they erupt at
about the age of 17 or 18 when people are supposed to begin to assume the
mantel of adulthood (I can only assume that this name must be a hangover from
centuries ago when people only lived to 25). During the course of
evolution, our the human face shrank, but the number of teeth did not
decrease as rapidly as the shortening of the jaws. Most people do not
have enough room in the dental arches for their wisdom teeth, and they tend to
remain fully or partially impacted, under the bone of the jaw, or at least
partly under the gums (as in the image above). In some cases, the wisdom teeth may remain impacted
all of a person's life without causing trouble, but in a high stress society, these
people are in the minority. What's stress got to do with it?
You'll see.
Pericoronitis
 The
image on the right shows angry, swollen gums just behind a second molar.
There is actually a third molar (wisdom tooth) buried under the swollen
gums. You might think that a tooth that is totally buried under the gums
should not come into contact with germs from the mouth, and thus should not be
prone to infection. Usually, however, the enamel on the crown of the impacted wisdom tooth
is in contact with the enamel on the crown of the second molar, which is erupted
and immediately in front of the wisdom tooth (see arrow on illustration below). Gums cannot attach to
enamel. Thus the gums lie over the crown of the wisdom tooth like a glove lies
over the hand, in close approximation, but not attached to it. Germs can
leak under the gums at the place where the enamel of the second molar contacts
the enamel of the wisdom tooth, Therefore, there is almost always a
communication between the germs that live in the mouth and the space surrounding
the wisdom tooth. It is a tooth you cannot brush. When your body's
resistance is normal, the germs surrounding the impacted tooth are kept at bay
by the body's normal immune system. But if the body's resistance is
decreased, th rough sickness or emotional stress, the germs can get the upper
hand and you find yourself with an infection around the wisdom tooth.
These infections are called "pericoronitis" which means
(appropriately), "an infection around the crown of an unerupted tooth".
Once you get a case of pericoronitis, it can be controlled
temporarily by a having the dentist clean around the tooth and following up with
a course of antibiotics. But pericoronitis tends to return at regular
intervals until the offending tooth is finally removed. Click on either
image above for more on pericoronitis.
The relationship of wisdom teeth to the sinuses
 As
you can see in the image to the right, the upper impacted wisdom tooth is in
very close approximation to the maxillary sinus. As a rule impacted upper
wisdom teeth cause few
symptoms if no obvious oral infection is present. But in the case of
peircoronitis,
the infection can sometimes be transferred to the sinus causing typical sinus
headaches and congestion. Conversely, the extraction of a wisdom tooth in
this location can occasionally cause
problems with the
sinus.
People ask all the time if the problems they are having with
their sinuses are caused by their otherwise non symptomatic impacted wisdom
teeth. The answer is that it is always possible that there is a
connection, but generally impacted wisdom teeth rarely cause sinus discomfort
directly unless an obvious infection like pericoronitis is present. I
usually tell my patients that in rare instances, the removal of these teeth can
be associated with the relief of chronic headaches, but there is no guarantee
that there is a connection between their headaches and their wisdom teeth.
It is more likely that the patient is suffering from some of the symptoms of
TMJ which are caused by the unconscious habit of grinding and clenching the
teeth (bruxing).
Click
here to learn more about dentally related headaches.
At what age
should the wisdom teeth be extracted?
Most oral surgeons prefer to wait until the roots of the wisdom teeth are
between 1/2 and 2/3 formed, about age 17 for boys or 16 for girls before extracting
them. The
main reason for this is that during this period, the normal forces of eruption
have generally allowed the tooth to erupt as much as is possible under the
circumstances, while at the same time limiting the depth of the extraction
socket due to the shorter roots. This means a simpler procedure involving less drilling of
bone and tooth in order to effect extraction. Extraction during this ideal
window of time reduces the incidence of
dry socket or other post-operative
complications.
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Cysts  Aside from pericoronitis, there are
two other complications associated with impacted wisdom teeth.
They both involve the uncontrolled expansion of the follicle (the
space in the
bone where the tooth was originally formed). This follicle is lined with cells which are supposed to
transform into the lining of the
sulcus
of the gums when the tooth erupts. But if they are kept submerged for too
long, they sometimes forget their original mission and begin to produce fluid
which expands the follicle causing a cyst.
These cysts can become very
large and cause distortion of the bone and face, and can lead to such weakness in the
bone the jaw may be prone to fracture.
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Amyloblastoma
The second, very rare complication
arising from uncontrolled follicular growth is a form of tumor called amyloblastoma.
This tumor is not considered a cancer because it does not tend to
metastasize (spread to other areas of the body), but it is locally invasive
which means that it grows uncontrollably and can cause major damage and weakness
in the bone if it is not thoroughly removed. Amyloblastoma is most likely
to attack young adult males. It is less frequent in females or older people of either sex.
Since it is always associated with an impacted tooth, usually a wisdom tooth,
(but not always, as seen in the images above) it
rarely occurs before the age of 18. It is difficult to remove entirely,
and the surgeon will usually perform a wide excision (ie. he takes a lot of
extra bone along with the tumor) just to be sure that he has removed it all.
Next page>>What
to do after an extraction
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