Types of dental crowns.
If you've been informed that your tooth requires a crown, a decision must be made about what type should be placed.
There are a number of factors that need to be considered when making this determination, including comparative strength and durability and overall appearance. It's the goal of our pages to outline these issues for you, so you can have an intelligent discussion with your dentist about which makes the best choice for your situation.
What are the different types of crowns?
There are three kinds of dental crowns:
The following paragraphs provide a brief description of each. Use their associated links for more information. (If you don't really know what dental crowns are, here's a brief overview.)
As their name implies, all-metal crowns are fabricated entirely out of metal. While the classic all-metal has a gold coloration, other types of dental alloys, some of which have a silver ("white") color, can be used too.
Metal crowns are typically chosen for those applications where great strength is required and cosmetic appearance is not a concern. More details... >>
These crowns are made entirely out of some type of dental ceramic such as porcelain. When they're fabricated, most types are handmade by a dental technician but some are milled out of a block of ceramic by machine. Both techniques offer their own advantages.
All-ceramics are typically placed in those situations where the tooth's aesthetics are of utmost concern (front teeth). Their primary disadvantage is that they're not as strong as the other types of crowns. More details... >>
Porcelain-fused-to-metal dental crowns (PFM's) can be thought of as a hybrid between their all-metal and all-ceramic counterparts. When they're fabricated, porcelain is fused to an underlying metal substructure in a high-heat furnace.
As advantages, these crowns offer good strength characteristics and a tooth-like coloration. More details... >>
Which is best?
You need to understand that there's no single type of crown that always makes the best choice. The right selection always varies depending on the needs of the patient's specific application.
Hopefully you'll take the time to use the links above. Then, once you've formed an opinion about what you think might be the best kind of crown, discuss matters with your dentist. Once they know what your thought process is, it won't take them long to steer you to the one that makes the best choice in satisfying both your concerns and dental needs.
Crown Basics -
Just in case you're not sure what a crown is, here are a few things you should know about them.
A) What are they?
Crowns are a type of dental restoration that fit over that part of a tooth that lies above the gum line. For all practical purposes, once one has been cemented in place, it becomes the new outer surface for its tooth.
B) How are they placed?
Making a crown for a patient involves the following steps:
1) Tooth preparation and impression taking.
The first step involves trimming the patient's tooth. Dental crowns generally need to be on the order of 2 to 3 mm thick (so they have good cosmetic and strength characteristics). That means that a tooth receiving one needs to be trimmed down by this same amount.
Once it's been properly shaped, the dentist will need to make a copy of the tooth that can be used to make its crown. In most cases, the dentist will do this using impress paste (a putty-like material that's squished over the tooth which then sets). As an alternative, the dentist may take an optical impression (a picture of the tooth that's then fed into a computer).
2) Crown cementation.
Once the crown has been fabricated, the dentist will check its fit, both on the tooth and the way it touches neighboring and opposing teeth. After making any needed adjustments, the crown is then permanently cemented onto its tooth.
C) How many visits does this process take?
Typically the steps outlined above are performed during two separate appointments. Usually these visits are scheduled about two weeks a part. During the time in between, the patient wears a temporary dental crown.
In the case where an optical impression is taken, a dental milling machine may be used that can grind the crown out of a block of ceramic in about 20 minutes. If so, the tooth can be prepared, and its crown cemented, in just one dental visit. (This technique variation is only available with all-ceramic crowns.)
D) Why do teeth require crowns?
Dental crowns are typically placed for the following reasons. Any one tooth may be in need of one or more of these benefits.
1) Restoring teeth to their original shape and function.
Crown placement is one way a dentist can rebuild broken teeth. Crowns, above all other types of dental restoration, create a very lasting repair.
2) Strengthening teeth.
Some teeth, especially back ones, may require crown placement because it is the type of dental restoration that can best withstand heavy chewing forces. Additionally, any fragile tooth, including those that have had root canal treatment, may benefit from a crown's strengthening effect.
3) Improving the appearance of teeth.
Since a dental crown becomes the new outer surface of a tooth, its cosmetic appearance can be vastly improved when one is placed. This includes tooth color, shape and even apparent alignment.