What are dental crowns?

In order to fit the crown in between your teeth without altering your bite, the tooth to be crowned needs to be trimmed. This trimming is performed on all surfaces of the tooth, with more trimming done on the biting surface so that the new crown will be strong enough to bite on without cracking. 

This is especially critical for crowns made of porcelain (including zirconia).

Crowns made of metal (such as gold alloys) can be made thinner without compromising strength. Your dentist may advise a metal crown for a tooth with a short crown height (the part of the tooth visible above the gum) to maximise available tooth structure.

Teeth with large fillings or cracks that compromise structural integrity are usually crowned to prevent severe fractures that require extraction. A crown is a good way to prevent this from happening.

Crown fees vary depending on the dental clinic, the case difficulty, the material used and the lab used.

Case difficulty determines how much time and skill will be required to perform the crown treatment. Patients with limited mouth opening, severely broken down teeth, multiple crowns and highly aesthetic crowns are cases that are considered difficult.

Crowns made of metals like gold cost more than non-precious metal or non-metallic crowns because of the alloy used. Gold is very long lasting, very strong and does not wear out the opposing teeth so it is still used in dental crowns today.

A good dental lab is an important part of making quality crowns. Dental technicians vary by skill and training. Good labs that do highly aesthetic crowns that fit well do not come cheap. The dental technician has to work closely with your dentist to deliver a high quality crown according to the requirements of the case.

A well-made and well-fitting crown can last for many years if it is maintained well by the patient.

Crowns can become damaged if decay develops under the margin or if the surface gets damaged by repeated wear and tear. Wear of the crown may be accelerated in patients who grind/clench their teeth (bruxism). To prevent this from prematurely damaging the crown, patients who are at risk of breaking their crowns will be fitted with a custom-made night guard to wear during sleep.

Your dentist will be able to monitor the crowns placed by examining them at your active maintenance appointments (every 4-6 months) and periodic dental x rays (bitewings).

A painful tooth (crowned or not) may be caused by pulpitis (inflammation of the nerve inside the pulp of the tooth) or a heavy bite.

Teeth that require crowns have often been through multiple rounds of dental treatment or have significant cracks in them. Some teeth may also have sustained traumatic injuries that have caused fracture of the tooth. These increase the risk of pulp irritation.

If the tooth has been heavily prepared (trimmed) for a crown, that reduces the thickness of the dentine layer that protects the pulp from bacteria. The amount of trimming required depends on the type of crown material that has been planned and the bite pattern planned. Severely worn teeth may be completely destroyed if prepared in the conventional way for the crown to fit into the current bite pattern.

Old crowns may have margins that do not fit well or may be undermined by decay. Open or leaky margins may cause sensitivity or dislodgement of the crown. Poorly-fitting crowns should be replaced to prevent loss of the tooth underneath.

For severe toothache, the treatment of choice would be a root canal treatment. This may be done by making a hole in the crown (which is patched up later).

After a new crown has been fitted, the bite may be heavier on the crown than on the unprepared tooth previously. This overloading of the tooth may cause transient tenderness on biting or even cold sensitivity. These symptoms can be easily managed by leveling the bite to ensure that other teeth share the load of chewing.

Your crown has been custom-made to fit a particular tooth.

First, the temporary crown has to be removed under local anaesthetic. Even a root canal-treated tooth should be numbed so that the surrounding gum tissue can be manipulated during the cementation process painlessly.

Once the temporary crown has been removed, the temporary cement and plaque is cleaned from the tooth surface. The crown is tried in to check for fit, colour and then the bite is checked. Your dentist may also take an x-ray of the crown to check the fit before cementation.

Once the fit and colour have been verified, the tooth is cleaned of saliva once again and kept dry. The fitting surface of the crown is also cleaned and may be chemically-prepared for the cement.

The cementation must take place in a dry environment to ensure that the cement sets properly. Sometimes, a rubber dam is used to ensure a dry field, especially for cementing certain types of porcelain crowns.

Once the crown has been attached to the tooth, excess cement is removed carefully. The bite is checked and refined once again. Another x-ray may be taken to check for cement remnants under the gumline.

An inlay is a lab-made filling. An inlay can be made of resin composite (a type of toughened plastic), porcelain or metals like gold. By definition, an inlay does not cover the cusps (the protruding parts of the tooth).

A crown is a cap that covers all the biting surfaces of the tooth. The crown margins may extend very close to the gumline (a full crown) or may stop quite high up the side of the tooth (an onlay).

An inlay does not reinforce weakened cusps, so is not suitable for teeth with large fillings/cavities or teeth that have been root canal treated.