A crown is a permanent covering that fits over an original tooth that is either decayed, damaged or cracked. Generally the dentist will recommend a crown when the damaged area is too large to be repaired by a simple filling. Certain teeth such as molars and premolars that have had root canals performed on them also require crowns once the root canal has been finished. Placing a filling in a tooth that actually needs a crown will frequently lead to the tooth fracturing or splitting. This often results in the need to extract the broken tooth. Crowns are made of a variety of different materials such as porcelain, gold, acrylic resin or a mix of these materials. Porcelain generally has the most natural appearance, although it is often less durable.
The treatment for a patient receiving a crown involves:
- Numbing the tooth to remove the decay in or around it.
- Re-sculpturing the tooth to provide an ideal fit for the crown.
- Making an impression of your teeth in order to create a custom-made crown.
- Making a temporary crown out of acrylic resin and fitting it onto the tooth during the interim period when the permanent custom-made crown is being created by a lab.
- Applying the permanent crown (when received from the lab) by removing the temporary crown and fitting the permanent one onto the tooth.
- After ensuring that the crown has the proper look and fit, the dentist cements it into place.
This process generally consists of 2 visits over a two to three week period. Once the procedure is completed, proper dental hygiene, including daily brushing and flossing, is required to maintain healthy, bacteria-free teeth, gums and crowns. This helps in the prevention of gum disease. Most crowns last an average of 15-20 years. However, given proper care, some crowns can last a lifetime.
If you are missing any teeth you may be able to replace the teeth with a bridge. A bridge consists of several crowns that are attached together. You can replace one or several missing teeth with a bridge. The bridge is attached to the teeth that are adjacent to the space that is missing a tooth or teeth. Generally, you need a good solid tooth on either side of the space to create a bridge. A cantilever bridge can sometimes be used when you have no tooth on the back side of a space but two good teeth on the other side. In cases were several teeth are missing you may need to involve more than two good teeth in the bridge to assure that it has adequate strength and support. The procedure for a bridge is the same as the procedure listed above for a crown except that it involves more than one tooth. Once completed, the bridge is cemented in place. It is not removable by the patient.
If you are missing too many teeth or have large spaces that do not have teeth on both sides of them, you may still be a candidate for an implant bridge.
Leaving spaces where teeth have been extracted can, over the long term, contribute to the following problems:
- The shifting of the remaining teeth
- The fracture of remaining teeth due to biting forces being spread out over fewer teeth
- The loosening of the remaining teeth
- TMJ and other jaw problems
- Occlusion problems
- Gaps opening between the front teeth
There are three main types of bridges, namely:
- Fixed bridge- this is the most popular and consists of a filler tooth that is attached to two crowns, which fit over the existing teeth and hold the bridge in place.
- The “Maryland” bridge can be used to replace missing lower front teeth and consists of a filler tooth that is attached to metal bands that are bonded to the backs of the abutment teeth. These are rarely done because they can frequently come off.
- The Cantilever bridge is often used when there are teeth on only one side of the span. A typical three-unit cantilever bridge consists of two crowned teeth positioned next to each other on the same side of the missing tooth space. The filler tooth is then connected to the two crowned teeth, which extend into the missing tooth space or end.