Crowns are a protective ceramic or gold cover custom made to fit over an existing tooth. They are often recommended following root canal treatment to protect the remaining tooth once the nerve has been removed.
What is a crown?
Crowns are complete cover/cap for a tooth. These restorations maybe required in a root canal treated tooth to protect the structure of the teeth. It may also be required in cases of heavily restored to prevent further loss of tooth structure. The tooth structure is prepared to receive this crown. During this preparation the tooth is shaped accordingly to the exact thickness as the crown to be placed.
What are crowns made of?
Crowns are made of a variety of materials and new materials are constantly introduced on the market. Different materials are used for different situations.
Ceramic Bonded To Precious Metal Crowns- is made of a precious metal base and porcelain is then applied in layers over the base to make it look like a tooth at conversational distance. This has been the most common type of crown made for the past 25 years.
Ceramic crowns- these crowns are not as strong as ceramic bonded to precious metal crowns but they can look very natural and are mostly used on front teeth and on people that do not grind their teeth. These are the most popular aesthetic restorations currently available and are used more and more here at Close Dental.
Composite crowns– these crowns are made of a resin (plastic) material and can look very natural. They are not as strong and smooth as ceramic crowns and are often used as a" short term" intermediate solution for full mouth reconstruction cases. These crowns help the patient to get used to repositioning of the bite and help to protect the remaining natural tooth structure in the meantime.
Veneers- the most popular procedure used in 'smile makeovers'. They are also often used to close small gaps, when orthodontics is not suitable. If one tooth is slightly out of position, a veneer can be fitted to bring it into alignment with the rest of the teeth. Veneers can protect teeth from further damage caused by acid in foods and drinks or from acids in the stomach that cause the teeth to wear away.
Precious Metal Crowns- Gold and palladium crowns are very strong and hard wearing and are usually used at the back of the mouth. They are most suitable for people who grind and clench their teeth. Many years ago the gold crowns was used in front teeth to indicate wealth.
How is a crown made?
The tooth will be prepared to the ideal shape for the crown. This will involve shaping the outer surface of the tooth leaving a core. The thickness of the crown will be the same as the amount of tooth that has been removed.
Once the tooth is shaped an impression of the prepared tooth will be taken and one of the opposite jaw and another to mark the way you bite. All the impressions will be sent to the technician to reproduce a crown that fits the tooth exactly. A visit to the laboratory may be needed to match the colour of the crown to the existing teeth. The prepared tooth will have a custom made temporary crown fitted until the new crown is made.
The treatment takes at least two visits to the practice and one visit with the laboratory, if needed.
While the crown is being made in the Lab, a temporary crown is placed over the prepared tooth. Sometimes the Lab technician will need to see the tooth to select the shade for the new crown in order to match it to the rest of the teeth.
When eating with the temporary crown it is important not to eat hard or sticky foods or you may knock it loose. If the temporary comes loose it is important that it is recommended by us.
Once the crown is made, the temporary crown is removed and the crown is checked for fit. Sometimes this will involve a radiograph. Once the fit is checked the crown is cemented to the prepared tooth.
How long will a crown last?
The life of a crown depends on how much pressure is applied on the bite and how well you look after it. The crown cannot decay, but decay can start where the edge of crown joins the tooth. It is very important to keep the gums and crown clean and visit your dentist and hygienist regularly. They last for many years if your oral hygiene conditions are ideal.
Porcelain and Metal crowns
The porcelain is fused to the metal making the porcelain metal crown. The metal is on the inside and porcelain covering it on the outside. The porcelain gives the aesthetics and the metal gives the crown the strength. Porcelain metal crowns are made where aesthetics is still important but the tooth needs to be as strong as possible, possibly because the tooth is very weak or heavy chewing forces. As a result of the metal, porcelain metal crowns do not have the same translucency as all-porcelain crowns but are stronger. Aesthetics sometimes can be slightly compromised but Lab Technicians can custom make the tooth to help overcome these problems.