Q What is
a crown?
A Crowns are an ideal way to rebuild teeth which
have been broken, or have been weakened by decay or a very large
filling. The crown fits right over the remaining part of the tooth,
making it strong and giving it the shape and contour of a natural
tooth. Crowns are sometimes also known as 'caps'.
Q Why would I need
a crown?
A There are a number of reasons.
For instance:
- the tooth may have been weakened by having
a very large filling
- you may have discoloured fillings and would
like to improve the appearance of the tooth
- you may have had a root filling which will need
a crown to protect it
- you may have had an accident and damaged the
tooth
- it may help hold a bridge or denture firmly
in place.
Q What
are crowns made of?
A Crowns are made of a variety
of materials and new materials are being introduced
all the time. Here are some of the options available
at present:
- Porcelain bonded to precious metal: this is
what most crowns are made from. A precious metal base is made
and layers of porcelain are then applied over it.
- Porcelain: these crowns are not as strong as
bonded crowns but they can look very natural and are most often
used for front teeth.
- Porcelain and composite: porcelain and composite
resin materials can sometimes look the most natural. However,
these crowns are not as strong as bonded metal crowns.
Glass:
these crowns look very natural and are used on both front and
back teeth.
- Precious metal (gold and palladium): these crowns
are very strong and hard-wearing, but are usually used at the
back of the mouth, where they are not visible.
Q How is a tooth prepared
for a crown?
A The dentist will prepare
the tooth to the ideal shape for the crown. This will
mean removing most of the outer surface, and leaving
a strong inner 'core'. The amount of the tooth removed
will be the same as the thickness of the crown to be
fitted. Once the tooth is shaped, the dentist will take
an impression of the prepared tooth, one of the opposite
jaw and possibly another to mark the way you bite together.
The impressions will be given to the technician, along
with any other information they need to make the crown.
Q Who makes the
crown?
A The impressions and information
about the shade of your teeth will be given to a dental technician
who will be skilled in making crowns. They will make models
of your mouth and make the crown on these to be sure that
the crown fits perfectly.
Q Will the crown
be noticeable?
A No. The crown will be made
to match your other teeth exactly. The shade of the neighbouring
teeth will be recorded, to make sure that the colour
looks natural and matches the surrounding teeth. A temporary
crown, usually made in plastic, will be fitted at the
end of the first appointment to last until the permanent
one is ready. These temporary crowns may be more noticeable,
but they are only in place for about two weeks.
Q How long does the treatment
take?
A You will need to have at
least two visits: the first for the preparation, impression,
shade taking and fitting the temporary crown, and the
second to fit the permanent crown.
Q Does it hurt to have
a tooth prepared for a crown?
A No. A local anaesthetic is
used and the preparation should feel no different from
a filling. If the tooth does not have a nerve, and a
post crown is being prepared, then local anaesthetic
may not be needed.
Q Are post crowns different?
A Post crowns may be used when
the tooth has been root filled. The weakened crown of
the tooth is drilled off at the level of the gum. The
dentist makes a double-ended 'post' to fit into the root
canal. This can be either prefabricated stainless steel
or custom made of gold. One end of the post is cemented
into the root canal, and the other end holds the crown
firmly in place.
Q Are there any
alternatives to post crowns for root-filled teeth?
A If a root-filled tooth is
not completely broken down, it may be possible to build
it up again using filling material. This 'core' is then
prepared in the same way as a natural tooth and the impressions
are taken.
Q How long will
a crown last?
A The life of a crown will
depend on how well it is looked after. The crown itself
cannot decay, but decay can start where the edge of the
crown joins the tooth. It is very important to keep this
area as clean as your other teeth, or decay could endanger
the crown. Properly cared for crowns will last for many
years - your dentist will be able to tell you how long.
Q How are crowns
fixed to teeth?
A Once the fit and appearance
of the crown has been checked - and approved by you -
it will be cemented in place with special dental cement.
The cement also forms a seal to help hold it firmly in
place.
Q Will the crown
feel different?
A Because the shape of the
crown will be slightly different from the shape of you
tooth before it was crowned, you may be aware of it to
begin with. Within a few days it should feel fine, and
you will not notice it. The crown may need some adjustment
if it feels higher than the surrounding teeth. If it
is at all uncomfortable ask your dentist to check and
adjust it.
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