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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