A dental crown is a tooth-shaped dental cap that your dentist puts to cover the crown portion of the tooth in order to provide your teeth with good aesthetics, function, and support.
Crowns are fixed prosthetic appliance providing support and strength to the damaged or weakened tooth or as a support to a bridge in case of missing teeth or implants.
These teeth crowns are also known in layman terms as teeth caps or dental caps, as these crowns cap around the tooth.
Dental Crown – Who Needs One?
Your dentist may prescribe a dental crown for you if you belong to one or more of the following categories.
Tooth Crowns In the case of Fractures
If you are a person with a fractured coronal portion (the crown portion of the tooth which is above the gum line and visible in the mouth) of the tooth with more than 1/3rd of the tooth tissue lost may need a crown. In such cases, the tooth may require root canal treatment depending on the vitality of the tooth and then a crown may be placed.
In The Case of RCTs
The teeth which are root canal treated usually tend to become brittle, discolored and weak over time. These teeth need supportive covering for better durability and function. So if you have such teeth in your mouth your dentist may advise you to go for a dental crown.
To Improve The Appearance
If your front teeth are aesthetically compromised, meaning the teeth don’t look good either due to a fracture or discoloration due to some reason, such teeth can be given dental caps or crowns. These crowns can enhance the appearance of the individual significantly.
Dental Crown In Case of Dental Bridges or Fixed Prosthesis
Teeth crowns are also done as a support to a dental bridge where there is a need for replacement of missing tooth/teeth. If one or more of your teeth are missing, then a bridge is done taking the support of teeth adjacent to the missing area.
The tooth on either side of the missing teeth is taken as the support for the upcoming dental bridge. These teeth are also called the ‘abutment teeth’. That’s done by placing a dental crown on each of that abutment tooth and attaching replaced tooth/teeth called Pontic to those crowns forming a bridge. This is a fixed prosthesis.
In Case of Implants
The crowns are also done over dental implants to improve the aesthetics and the overall function.
In Case of Large Fillings
If you have a tooth that has a large filling, chances are that the tooth has lost most of its structure and lacks the strength to bear the masticatory load. In such cases, your dentist may ask you to go for a dental cap to improve the stability and strength of the tooth in question.
Types of Dental Crowns
Stainless Steel Crowns
Children who have their primary molar tooth treated endodontically, are given the stainless steel crowns. Adults with root canal treated or fractured back teeth can be given stain steel crowns as the back teeth aren’t visible.
Metal Ceramic Crowns
This type of crown has the external/visible ceramic part which is white in color and has the inner metal part to increase the strength of the crown. Both of these parts are bonded together to synthesize the tooth crown.
Porcelain Jacket Crowns
This type of crown is done when aesthetic is of prime concern. This is usually done in the anterior teeth.
All Ceramic Crowns
Ceramic has good aesthetic property as well as high tensile strength. The all ceramic crowns are better compared to other crowns when it comes to strength and stability. But at the same time, they are very expensive.
Post Core Crowns
When there isn’t enough tooth structure to place a crown, the support of root dentine is taken by placing a post in the tooth. This post acts as an anchor over which the crown is placed.
There are different types of post core systems. There is prefabricated post core, cast post core systems. The type of post-core depends on the patient’s need and tooth condition.
How are Dental Crowns Made?
Tooth crowns come under the fixed prosthetic appliances category and are fabricated in the laboratory. Crowns can be made using different types of materials.
The type of material used usually depends on the patient’s requirements in terms of cost, the condition of the tooth, the general condition of the mouth, the amount of tooth structure left, the location of the tooth, etc.
Clinical Steps Involved
There are certain clinical steps that need to be followed by the dentist to fit the crown perfectly on to the tooth.
Tooth preparation involves removal of some amount of tooth structure uniformly from around the tooth to allow the crown material to fit in. The crown needs to fit perfectly without interfering with occlusion (bite) and at the same time provide strength to the tooth.
The tooth preparation should have smooth finish lines with minimum damage to the gingival tissues.
There are different types of finish lines depending on the material used to make the crown. The finish lines are done using high-speed diamond burs.
- Butt Joint finish lines are usually done for porcelain jacket crowns
- Chamfer lines are done in case of ceramic crowns
- Taper finish lines are done for full veneer crowns
The prepared tooth needs a temporary crown until the final crown is done. The reason being mainly aesthetics, pulp protection or preventing any drift or movement of neighboring teeth.
There are different types of temporary crowns available like the polycarbonate crowns, stainless crowns, acrylic crowns, etc. These crowns are cemented on to the prepared teeth using temporary cement.
A good impression of the prepared tooth is very important if the crown needs a good fit.
There are different kinds of impression materials like polyvinyl siloxane, polyether, polysulfide. The impressions are made using impression trays.
Casts are made out of the impressions made and kept ready to be sent to the lab for a further crown preparation.
The dentist needs to give the correct information regarding the crown type, shape to the lab technician.
Dental crown cementation
- First, the temporary crown needs to be removed.
- Then the permanent crown try-in will be done to check for the fit of the margins, contact points, and occlusion.
- When the dentist and the patient are satisfied with the fit, the final cementation of the crown is done using permanent luting cement. The margins are cleaned and oral hygiene instructions regarding the crown will be given.
- If there is any doubt about the fitting of the crown, the dentist may use temporary cement for cementation. In such a case, the patient will need to follow up with the dentist at a later date.
- Finally, with a dental cap in your mouth, you need to follow a good oral hygiene regimen to ensure the longevity of the dental crown.