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A
crown fits over the entire top of the tooth above the
gum line. Crowns cover, protect, seal and strengthen
a tooth. A crown is needed when a filling
just will not work. A crown may be made of white porcelain,
or porcelain fused to gold. There are many situations
that may call for a crown:
Large
decay. If a tooth has
decay so deep and large that a filling
will not stay, or if the tooth structure is weakened,
a crown must be placed on the tooth to save it.
Large
old fillings. When large
old fillings break down, or get decay
around them, they usually need to be crowned. It is
important to crown a tooth that has been structurally
weakened to prevent a cracked or broken tooth. Once
a tooth breaks, it may not be possible to save it.
Cracked
tooth. When a tooth is cracked, a filling
will not seal the crack. A crown has to be placed over
the tooth to hold it and the crack together. If a crown
is not placed on the tooth, the tooth will become sensitive
to chewing pressure, or will eventually break. It is
important to crown a cracked tooth before it
breaks, because in some cases a broken tooth cannot
be crowned and must be extracted.
Broken / Fractured tooth.
A tooth that has broken is usually too weak to hold
a filling. A crown will hold
the tooth together and prevent it from breaking again.
If the fracture involves the nerve, Root
Canal Therapy may be required before the tooth is
crowned. In some cases, a broken tooth cannot be saved
and must be extracted.
This
patient chose not to have the cracked tooth above crowned,
and it later fractured. This tooth had to be extracted
because it cracked all the way to the root.
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Sensitive teeth.
Teeth that are very sensitive, either from a lot of
"wear", or from receded gums, sometimes require crowns
to seal and protect the teeth from hot and cold sensitivity.
Root Canal Therapy.
A tooth that has undergone Root Canal Therapy will need
a crown to properly seal and protect the tooth. A tooth
with Root Canal Therapy is more brittle than a tooth
with a healthy nerve and blood supply. A crown provides
the necessary support to the tooth.
In cosmetic dentistry, crowns (sometimes
called "caps") are used less frequently
since the advent of veneers,
but in some cases a crown may be necessary for a particular
tooth. A tooth with a bad fracture
or a large filling may be
a candidate for a crown instead of a veneer.
Before:
This tooth has a large filling as shown. A crown
is needed on this tooth, instead of a veneer, because
there isn't enough natural tooth left to support a veneer.
A crown will cover and protect the tooth, but will look
the same as a veneer.
After:
The top teeth now have veneers, except the one that
had the large filling, which now has a crown.
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