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In
dentistry, crowns and bridges refers to the restoration of natural teeth
that have been damaged, decayed or lost. A crown can be made to restore
an individual tooth damaged by decay or fracture back to it's original
form and function, while a bridge is used to replace one or more missing
teeth. These restorations are cemented onto the teeth and are referred
to as "fixed" dentistry as opposed to a restoration of missing teeth
with a removable appliance or partial denture.
Both
procedures require the use of a local anesthetic and the grinding or
preparation of the teeth, with a crown, the damaged tooth, with a
bridge, the adjacent teeth. A badly decayed or broken tooth may require
that the tooth be "built up" with a special restorative material during
the preparation of the teeth. With a fixed bridge, the prosthesis will
span the area of a missing tooth, known as a pontic, while the two or
more adjacent supporting teeth are called abutments. An impression is
taken of the prepared area, and a temporary crown or bridge is placed.
The permanent crown will fit considerably better than the temporary
crown, so the temporary crown gives little indication of how the final
crown will fit or feel. It is important that the temporary crown or
bridge stay in place until the final crown or bridge is placed. If the
temporary should come off early, please call the office.
After about two weeks, the crown or bridge is ready to be fitted,
adjusted, and cemented in place.
Crowns and bridges can be made of several materials. Full gold crowns
and porcelain fused to metal crowns are normally done on the very last
teeth in the mouth where strength is most important and appearance is
less important.
Porcelain fused to metal offers most of the strength of full gold, but
the esthetics of a tooth colored crown. A thin layer of "High Noble
Metal" is made to exactly fit over the prepared tooth model, then
porcelain is layered and fired in a ceramic oven at over 2000 degrees,
till the desired shape and size is achieved. Most of The Dentist's crowns
are of this variety.
Front teeth can be restored with porcelain fused to gold, but sometimes
an all porcelain crown is used. With porcelain fused to gold and all
porcelain crowns, the color of the porcelain is
shaded to match the existing teeth, or in some cases, lighter to
cosmetically brighten the smile.
Some of the indications for a crown are:
-
A previously filled tooth where there now
exists more filling than tooth. The existing tooth structure becomes
weakened and can no longer support the filling.
- Extensive damage by decay.
- Discolorations and compromised esthetics.
- Fractures.
-
Root canal - After root canal, teeth tend
to become brittle and are more apt to fracture. These teeth need to
be protected by a crown.
- Bridges are recommended to replace one or
two missing teeth. They require healthy adjacent teeth to support
the replacement teeth.
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