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Crowns

Overview:

A dental crown replicates the exposed tooth segment above the gums when a tooth is severely decayed or damaged. Some people refer to it as a dental cap. There are several circumstances why you may or will require a crown. This usually occurs when the tooth requires restoration that cannot be achieved with the other filling materials, such as amalgam and composite fillings. It also encompasses the tooth making it stronger. Dental crown are made by a dental laboratory so that they fit properly. There are also prefabricated stainless steel and acrylic crowns that can act as interim tooth coverings while the final crown is being prepared. These interim crowns also keep the surrounding teeth from shifting.

Crowns are fabricated out of several different materials, and are best classified as: all metal (i.e., gold and mixtures), porcelain and metal (PFM), and all porcelain or ceramic. The metals usually include some gold and different strong metals. These crowns and PFM crowns are the best choices for the molars and premolars, and ceramic crowns are more likely used for the front teeth. The ceramic and PFM crowns are shade-matched with your existing teeth and should have a natural appearance. Crowns usually last anywhere from 7-40+ years. The usual failure factor is usually the cement.

Tooth Preparation:

At times your dental caries will extend into the pulp of the tooth, and a root canal may be required before the crown is prepared and fabricated. However, not all crowned teeth require root canal. If the decay is very widespread, the dentist must build-up the tooth prior to preparing it for the crown. This is either done with pins and filling material, or if a root canal was required, a post and filling material.

Your dentist will prepare the tooth be removing the enamel and a portion of the dentin with specially designed dental drills. Then gingival cord is placed around the tooth below the gingival tissue to separate the gum tissue from the tooth for an accurate mould of the tooth. An impression of the tooth is then taken, along with an opposing impression, and bite registration. A shade is then chosen and these are all placed into a dental laboratory pan with instructions for the dental laboratory technician. During this time, the patient will wear a temporary crown made by the dentist, to make sure that the surrounding teeth do not shift, and the exposed (i.e., sensitive) dentin is covered. This is then cemented on with temporary cement. When the crown is returned from the dental laboratory, the temporary crown is removed and the final crown is then fitted and cemented with strong cement.

Following Placement:

There should be no sensitivity on this tooth after the final crown is placed if the tooth had a root canal. If it didn't have a root canal, some temporary sensitivity may be present for a day or so due to tissue manipulation. There can be some discolouration around the gum line of a PFM crown, due to the metal showing through. However, if the tooth was adequately prepared and the crown was fabricated properly, this usually doesn't happen on the facial side of the crown.

Crowns do not protect against gum disease(s), therefore proper oral hygiene must be performed. Some crowns have been known to chip, and may be fixed without removing the crown, or may require crown replacement. The cement may also wash out beneath the crown and if it falls out, it can be recemented. However, if the crown doesn't fall out, decay can form below the crown and cause more serious problems that can go unnoticed for a long time. If your crown feels loose, contact your dentist.

If your crown does fall out, do not lose it or throw it away. Instead, put it in a container or zip-lock baggie and bring it to your dentist with you. Don't try to recement it by yourself. Your dentist must evaluate why the crown fell out and also if there is any additional tooth damage or decay in your tooth before replacing the crown. If away on a business trip or vacation, locate a local dentist that can help.