Last Updated: Feb 15, 2013
A dental crown restores a tooth's shape, size, strength and appearance by encasing the tooth in a custom molded cap.
Crowns usually last from 5 to 15 years. Its life span depends on the amount of wear and tear that the crown is exposed to; how well the patient follows good oral hygiene practices; and his/her personal mouth-related habits (clenching teeth, chewing ice, biting fingernails and using teeth to open packaging). Crowns of acrylic or stainless steel are often used as a temporary restoration until a permanent crown is built in a dental laboratory.
Why Get Dental Crowns?
Dental specialists recommend crowns to:
- Protect weak teeth from breaking
- Hold together parts of a cracked tooth
- Restore a broken or severely worn down tooth
- Hold a dental bridge in place
- Make a cosmetic modification
- Cover and support misshapen or discolored teeth, dental implants, or a tooth with a large filling when there isn't a lot of tooth left.
Differences in Crown Materials
Porcelain fused to metal crowns are color matched to a patient's adjacent teeth. However, more wearing to the opposing teeth occurs with this crown type compared with metal or resin crowns. Porcelain portions of the crown can also chip or break off.
Next to all-ceramic crowns, porcelain-fused-to-metal crowns look the most like normal teeth. However, sometimes the metal underlying the crown's porcelain can show through as a dark line, especially at the gum line and even more so if a patient's gums recede. These crowns can be a good choice for front or back teeth.
All-resin dental crowns are the least expensive,though more prone to fractures than porcelain-fused-to metal crowns and wear down over time.
Ceramic or porcelain dental crowns – a good choice for front teeth - make the best matches to a patient's natural teeth color and are more suitable for people with metal allergies. However, they are not as strong as porcelain-fused-to-metal crowns and wear down opposing teeth a little more than metal or resin crowns.
How to Prepare?
Placing dental crowns requires two dentist visits; a comprehensive examination followed by tooth prep work:
The comprehensive examination of the tooth and the surrounding bone area is conducted to ensure that the tooth has no extensive decay, infection or injury to the tooth's pulp and that there is no need for root canal treatment. The tooth prep work involves applying anesthetics in the tooth and gum tissue around the tooth then filing down the chewing surface and sides of the tooth to make room for the crown. If a large area of the tooth is missing due to decay or damage, filling material is used to build up the tooth to support the crown.
Once the tooth is reshaped, an impression of the tooth is taken to make the crown mold. To ensure that the crown will not affect a patient's bite, additional impressions of the teeth are taken above and below the dental crown. Then, a temporary crown is placed on top of the tooth to cover and protect the prepared tooth while the impressions are sent to a lab to manufacture the crown. Crowns are delivered to the dentist's office within two weeks.
Mounting the Permanent Dental Crown
During the second visit, the dentist will revise the fit and color of the permanent crown, apply local anesthetic to numb the tooth, remove the temporary crown, and cement the new crown permanently.
Caring for Temporary Crowns
Patients are encouraged to:
- Avoid sticky, chewy foods (chewing gum, caramel) that may grab and pull off the crown.
- Minimize the use of the side of the mouth where the temporary crown was mounted by shifting the bulk of chewing to the other side of the mouth
- Avoid chewing hard foods (such as raw vegetables) that may dislodge or break the crown
- Slide flossing material out-rather than lifting out-when cleaning teeth
- Lifting the floss out, as done normally, might pull off the temporary crown
Patients with crowns may experience sensitivity or discomfort as the newly crowned tooth may be sensitive after the procedure. Patients may experience some heat and cold sensitivity if the tooth has a nerve. A special brush and toothpaste are recommended for this type of issue. Patients also may experience pain or sensitivity when biting down when the crown is too high on the tooth. If this is the case, patients should make an appointment with a dentist to assess and correct it.
Crowns made from all porcelain can sometimes chip. Small chips can be repaired with composite resin while the crown remains in the mouth. Otherwise, the crown may need to be replaced.
Crowns become loose when their cement erodes from under them. It is recommended patients call their dentist immediately to avoid bacteria leak and cause further decay to the tooth if this happens.
Crown Falls Off
Crowns may fall off due to an improper fit or a lake of cement. Contact a dentist immediately and follow the specific instructions on how to care for the tooth and crown until the next appointment.
Patients rarely experience allergic reactions to the metals or porcelain used in crowns.
Dark Line at the Gum Line of Crowned Tooth
Crowns may show a dark line next to the gum line of the crown tooth. This is typical of the porcelain-fused-to-metal crown, as the metal shows through near the gum line.