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CROWNS
A crown, often referred to as a "cap", is a tooth restoration
that fits over an entire tooth (the area above the gumline, that is).
Crowns are usually placed on teeth which are badly broken down or weakened.
Crowns are also almost always placed on teeth that have undergone root
canal therapy. Most crowns done today are either all-porcelain,
or porcelain fused to a metal substructure to add strength. Invariably,
the cosmetic results are excellent, especially using the exceptional
materials now available.
PROCEDURE
In order to fit a crown over an existing tooth, the tooth must be
prepared by reshaping it into a form which will allow the crown to
be seated onto the tooth. This typically involves shaving down most
of the enamel covering of the tooth under local anesthetic. Once
the tooth is reshaped, an impression is taken from which a plaster
model of the tooth will be made for use in the dental laboratory.
A temporary crown will then be cemented onto the tooth, to remain
in place until the permanent crown or crowns are completed by the
laboratory.
Crowns typically require two to three weeks of lab time. Once ready,
your temporary crown is removed, and the permanent one cemented in
place, after checking for correct shade and fit.
BRIDGES
Often a tooth or teeth will be missing between other teeth.
This gap can be filled with a permanent functional replacement
tooth by using the teeth on either side of the space as a means
of support. This type of restoration is called a bridge. A bridge
is composed of crowns placed on the teeth adjacent to the gap,
connected by an artificial tooth or teeth which replace the missing
ones. The crowns which support the bridge are called abutments.
The replacement teeth which are connected to the crowns are called
pontics. Bridges are permanently cemented in place, and, even
though the teeth are connected, they appear to be separate and
distinct.
Bridges are often confused with partial dentures. Partials, however,
are removable and usually grip the supporting teeth with
visible metal clasps.
Bridges have been the standard treatment for replacement of one or
two missing teeth for several decades. They tend to be highly predictable
in longevity (often last a lifetime), and even for front teeth are
excellent esthetically. The chief drawback is that the abutment teeth
must be prepared for crowns, which often involves shaving down a
virgin tooth which would not otherwise need a crown. Fortunately,
this is more of a theoretical and psychological disadvantage than
an actual one, and before the introduction of dental
implants, also unavoidable. Now that the success rate of implants
is so high, however, many patients choose implants over bridges.
In many instances this is a choice based on personal preference,
as the cost is usually comparable for a bridge vs. an implant supported
crown.
PROCEDURE
The procedure for making a bridge is almost exactly the same as
that for crowns, except for the time factor involved. The reason
for this is that usually two teeth must be prepared for crowns
instead of one.
Note: Most bridges are done in order to replace only one or two
missing teeth, but bridges can also be made to replace multiple
missing teeth in certain circumstances.
Missing
Tooth |
Missing
tooth
replaced by bridge. |
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PROCEDURE
The procedure for making a bridge is almost exactly the same
as that for crowns, except for the time factor involved. The reason
for this is that usually two teeth must be prepared for crowns instead
of one.
Note: Most bridges are done in order to replace only one
or two missing teeth, but bridges can also be made to replace
multiple missing teeth in certain circumstances.
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