| 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.
These temporary crowns may be more noticeable, but they are
only in place for about two weeks unilt your permanent one
is ready.
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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