Dental crowns

A crown (often called a cap) fits over and replaces the entire part of a decayed tooth above the gum line. It encases the tooth and becomes the tooth's new outer surface.

You may need two or more visits to your dentist to repair a severely decayed tooth with a crown.

Crowns may be made of porcelain or a metal base covered with a thin layer of ceramic that matches your teeth and looks like a normal, healthy tooth. Crowns for the teeth in the back of the mouth may be made of gold.

During your first visit, your dentist will take out the decay and make an impression of your teeth to create a mold used for making the crown. The crown may be temporary. In this case, you will need a second visit.

A crown is used to:

• Treat teeth that have broken or decayed so much that your dentist cannot fix them with a filling.
• Cover a tooth that is so severely damaged that most of the top part had to be removed.
• Repair a defective filling.
• Improve how a tooth looks.

Dentists sometimes use crowns after root canal treatment to seal the tooth and prevent it from breaking.

Your dentist will start by numbing your teeth, gums, tongue, and surrounding skin. First the dentist will put a substance that feels like jelly directly on the area. This starts the numbing process. Then the dentist will inject an anesthetic to complete the process. Some dentists will give you nitrous oxide gas (laughing gas) to reduce your pain and help you relax.

Some dentists use a small sheet of rubber on a metal frame (rubber dam) to target the decayed tooth. This can stop liquid and tooth chips from entering the mouth and throat.

Your dentist will drill out all the decay. Next, the dentist will take an impression of the decayed tooth. The mold will allow a technician to make a crown that perfectly matches the drilled tooth.

The dentist will then cover the tooth with a temporary crown until your permanent crown is ready. Some methods don't require a temporary crown.

If you need a second visit, your dentist will:

• Remove the temporary crown.
• Cement the permanent crown to the damaged tooth.
• Have you bite on a piece of marking paper. This shows how well the crown is positioned. Your dentist may need to reshape and polish the crown.

A crown will work just like a healthy tooth. Crowns sometimes come loose or wear out over time. So you may need to get a crown cemented again or replaced.