What are they?
The crown of a tooth is that part which is visible in the mouth. An artificial crown completely covers a weak tooth above the gum line and protects it.
Crowns are made of metal or porcelain, or porcelain with metal inside for strenght.
What will the dentist do?
He will shape the tooth so that, with the artificial crown, it will be the same size as a normal tooth.
Preparation time will depend on how damaged the tooth is and whether it needs to be built up with a filling first.
The tooth might have to be root-filled first - this is sometimes called 'removing the nerve'. The crown is sometimes held in place by a peg in the root canal if a lot of the tooth is missing.
The dentist will use a soft mouldable material to make exact 'impressions' of the tooth that is to be crowned and the nearby teeth. A dental technician uses the impressions to make the crown the exact height and size needed.
A thin cord may be used to hold the gum away from the tooth so that the impressions is accurate round the edges.
A temporary crown made of plastic or metal is put over the tooth until the permanent crown is made. You can chew on a temporary crown but it won't be as strong as the finished one.
When the crown is fitted, the dentist will make adjustments to make sure you can bite comfortably. The crown is tried on first, and then glued into place.
What are the benefits?
A crown is strong and can look and feel exactly like a natural tooth. The colour and shape can be matched to your own teeth.
Depending on the strength of the tooth underneath, a crown can last for many years if you look after your mouth and teeth and the crown is not accidentally damaged.
Crowns can also improve the appearance of misshapen or discoloured teeth.