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 plac
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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