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 your 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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