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.
