- Wear:
Although there are a number of
factors that affect the life of a
dental restoration, the average
silver filling, crown or bridge may
last from five to 15 years,
depending upon the size. The average
composite (plastic
tooth-colored filling) may only last
half as long. Forces constantly
exerted on the fillings by chewing
and grinding cause them to wear
down. In some cases the porcelain
or gold in crowns actually
wears through from constant grinding
by the opposing teeth!
- Leakage:
Fillings may start to leak around
their edges due to wear and trauma.
Often leakage on the biting
surface of a crown goes
unnoticed by patients. This allows
bacteria a ready access to the
deeper areas of the tooth. Once the
bacteria are inside the tooth
or crown, they cannot be
removed, and decay may begin rapidly
again. Worst of all, this damage is
often unseen and there may be no
symptoms until the decay has reached
the nerve (pulp) of the tooth.
- Recurring
Decay: Increased exposure
to the elements that caused the
original cavity make it possible to
get another cavity in the same tooth
near the original filling. (Even the
best filling is not as smooth and
impervious to decay as healthy tooth
structure.) If a tooth is not kept
clean, decay can start near
the edge of the filling or in
another site on the tooth. Even if a
tooth has a crown covering it, decay
can still start at the edges where
it rests on the tooth, if it is not
kept clean. As mentioned before, if
decay is left untreated, it can
eventually invade the nerve of
the tooth, causing an abscess,
which leads to root canal or
extraction.
- Cracks:
A great deal of force is placed on
your teeth every day. The average
human bites with several hundred
pounds of pressure per square inch.
This biting pressure can result in
tiny cracks in the tooth.
Chewing on very hard substances,
such as ice or nuts, can crack a
tooth or filling. Often, you dentist
can tell when these cracks have
undermined another portion of the
tooth or gone too deep.
- Chips: If
the cracks are not repaired in time,
the tooth may break or chip.
Sometimes this will necessitate a
larger, more costly restoration.
Often, these teeth will require
crowns. Cracks can also form in the
porcelain of a crown. Thus,
chipped porcelain may
eventually brake off, as well. Your
dentist may feel it is better
to schedule a replacement crown
before this happens.
- Esthetics:
Over time, fillings begin to
tarnish (if they are silver) or
stain (if they are composites).
While this may not cause any direct
harm to the tooth immediately, it
does detract from the esthetics of
the mouth. Thus, some patients may
wish to replace their outdated
silver fillings with more
esthetic ones made of
tooth-colored composite or
porcelain.
- Periodontal
(Gum) Disease: Many
patients are unaware that most teeth
are lost due to gum disease, not
decay. If left untreated,
periodontal disease progresses, and
the gum tissues move lower on the
root. Eventually, bone is lost and
teeth become loose. In such cases of
periodontal involvement, your
dentist may find it necessary to
remove an old crown next to a loose
or missing tooth and replace it with
a new bridge.
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