Dental Crowns
A crown is a tooth-shaped cover that is placed over a tooth. It is meant to cover a tooth that was badly damaged or decayed. A crown is also known as a cap. It is made so that it looks like your tooth.
Crowns may be placed on your teeth for several reasons. Generally, the reason is to cover a tooth that has been extensively damaged by decay or breakage. Filling material is not good enough to replace the missing tooth structure. It can not make the tooth strong enough either. A crown may hold together parts of a cracked tooth and may even be used to hold a bridge in place. Crowns are used for cosmetic purposes in order to cover misshapen or badly discoloured teeth.
Crowns can be prefabricated or they may be manufactured in a laboratory. Prefabricated crowns are made of plastic or stainless steel. They may be used as a temporary restoration until a permanent crown is manufactured. In some cases, the prefabricated crowns may be used for the permanent restoration itself.
Crowns can be made of metal, porcelain fused to metal or PFM, or entirely ceramic. Metals used include gold, alloy, palladium, or a base metal alloy like nickel or chromium. The all-metal or PFM crowns are stronger and are better choices for molars and premolars. The PFM and all-ceramic crowns look exactly like normal teeth. These crowns last for at least seven years. In some cases, they may even last even longer. Some patients have their crowns still intact after forty years.
How do you prepare the tooth for crowning?
If you need a crown, you may also need to have endodontic or root canal treatment. Your tooth may have gone through extensive decay already and there will be risks of infection or injury to the pulp of the tooth. Not everyone who needs a crown will have to go through root canal treatment.
Aside from the crown, your dentist will need to build the foundation to support the crown. This foundation is needed if large areas of the natural tooth structure are decayed, damaged, or missing already. If you are getting the crown after a root canal treatment then your dentist may insert a post-and-core foundation.
In order to place a crown, your dentist must file down the tooth and make room for it. If you have an all-metal crown, less tooth structure will be removed. These crowns are thinner than PFM and all-porcelain ones.
After the tooth has been filed down, your dentist will use a piece of thread or cord to push the gum down around the tooth. An impression of the tooth will be made. The impression material sets in for five to six minutes and then it is removed. Your dentist will also take an impression of the teeth above or below the tooth that will receive the crown so that your bite will not be affected.
The tooth impressions are sent to the lab and your crown will be made. During this time, you will have a temporary crown. The crowns are mostly made out of plastic. They will be made in your dentist's office on the day of your visit. These temporary crowns are not meant to last. If a temporary crown is left in the mouth, the cement will eventually wash out and the tooth will decay.
On your second visit, your dentist will remove the temporary crown and test the permanent one. Sometimes, the crowns need additional polishing or glazing. Some other adjustment may have to be made as well. When the crown is ready, it is cemented permanently on your tooth.
What happens after your tooth is crowned?
You should not feel any discomfort or sensitivity after a crown has been installed. If there are still nerves in your tooth, they may be sensitive to changes in temperature. If you notice any pain or sensitivity when you bite then you should contact your dentist right away. This means that the crown has been placed too high on the tooth. This can be fixed easily.
You may notice a dark line next to the gum line on your crowned tooth specifically if you have a PFM crown. This dark line is the metal of the crown showing through. It is completely normal. A crowned tooth is not necessarily protected from all tooth decay and gum disease. You must continue practicing good oral hygiene after your crown has been installed.
Crowns can chip especially the ones made out of porcelain. This can be repaired in your mouth. Your dentist will etch the porcelain with acid and bond the composite resin to it. This will fix the chip. If the chipping is extensive then you may need to replace the crown altogether.
It is possible that the cement under the crown will wash out. The crown will remain in place and this will encourage bacteria to form underneath. This will cause decay. If your crown becomes loose then you need to contact your dental office right away.
In some instances, your crown may fall out because of the lack of cement or because of an improper fit. If this happens then you should clean the crown and the tooth. You can replace the crown using denture adhesive or temporary cement for the meantime. Contact your dental office right away and try to schedule a visit as soon as possible. If you are away from home then you must seek a dentist in the area who can fix the problem. You may need to get a new crown or you may need to re-cement the old crown on the tooth once more.