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Table of Contents

Magill’s Medical Guide, 9th Edition

Crowns and bridges

by Bethany Thivierge, , MPH, ELS

Category: Treatment

Also known as: Restorative dentistry, indirect restora tions

Anatomy or system affected: Mouth, teeth

Specialties and related fields: Dentistry

Definition: Structures that restore the function of the mouth after teeth have been broken or lost. A crown covers and protects a single tooth, while a bridge is a false tooth suspended between two crowns to replace a missing tooth.

Key terms:

abutment: a tooth protected by a crown that serves to anchor one end of a bridge

indirect restoration: a restoration that is fabricated outside the mouth, such as a crown or bridge

restoration: an item or material that is used to restore the structure and function of a compromised tooth

root canal: treatment in which the nerve and pulp of a damaged or infected tooth are removed

INDICATIONS AND PROCEDURES

A crown may be needed to protect a tooth from cracking or breaking, especially one that already has a large filling. It may also be used to cover a tooth that has already broken, become infected, and required endodontic treatment (commonly called a “root canal”). A crown provides a whole new chewing surface, so it must be able to withstand tremendous jaw pressure. Crowns are indirect restorations that may be made of tooth-colored porcelain, ceramic, or resin; metal, preferably gold; or a combination of porcelain and metal. In this combination, the porcelain is fused to gold, palladium, or platinum. In all-metal crowns, gold is preferable because it can be cast accurately for a tight fit and it will not corrode. In some cases, all that is needed is a partial crown, or onlay, which preserves more of the natural tooth beneath.

The first step in the preparation of a crown is to modify the tooth to receive a crown. Then, an impression of the tooth is made, and from this, a mold is made in which to cast the crown. Once produced, the crown is polished and contoured to approximate a natural tooth. Any porcelain is colored and glazed to match the shade of the patient’s natural teeth. Once the crown is finished, the dentist adjusts its fit in the patient’s mouth and secures the crown in place with a photosensitive resin. This process has traditionally been accomplished in two visits; the patient is given a temporary crown, usually acrylic, to wear while the permanent one is being made.

A bridge is indicated when one or several teeth in a row are missing and there are stable teeth on either side of the gap to serve as abutments. It is important to fill the gap to maintain optimal function for chewing and speaking by preventing the remaining teeth from shifting and losing their proper alignment.

Models of the patient’s mouth are made that indicate the shapes and positions of the abutting teeth that will receive crowns to support the bridge and the gap to be filled by the artificial tooth or teeth. The components of the bridge may be made of metal, porcelain, or a combination of the two. The dentist will indicate to the bridge fabricator what shade from a standard color system to make the porcelain to best match the patient’s natural teeth. Once the bridge is made, the dentist adjusts the fit in the patient’s mouth and cements the bridge in place. The entire process may require several visits; the patient is given a temporary acrylic bridge to protect the area while the permanent one is being made.

USES AND COMPLICATIONS

Because the preparation of crowns and bridges involves drilling on teeth, the dentist provides local anesthetic to numb the area. This numbness may last a while, and the patient must be careful not to bite the lips or tongue.

While the permanent restoration is being fabricated, the patient wears a temporary piece that is held in place with a light adhesive so it may be easily removed later. However, it may become dislodged before the next dental appointment. It is important that the temporary crown or bridge be replaced as soon as possible to keep the prepared teeth protected and stable. Should their shape or position change, the finished restoration would no longer fit properly.

Fabricating and fitting indirect restorations requires skill and patience. Any excess space inadvertently left between the tooth and the crown or bridge increases the risk of decay or infection because food may become trapped. This is especially problematic for teeth that have not had root canal treatment because a painful abscess may form under the crown. Excess space in bridgework creates the possibility of teeth shifting, which the bridge was originally designed to avoid.

When the crown or bridge is delivered, it might feel high and contact the teeth on the opposite jaw sooner than expected. The dentist will make adjustments at the time of delivery, but a return visit may be necessary if further discomfort is felt.

The teeth involved may be somewhat sensitive to cold following delivery of the restoration. This sensitivity may last for weeks, but it typically resolves on its own.

PERSPECTIVE AND PROSPECTS

Indirect restorations were initially unattractive but functional metal structures. Later, fabrication with porcelain allowed for a less obvious appearance. Advances in materials science have led to the development of stronger, more fracture-resistant ceramics. These contribute to longer lasting, more aesthetically pleasing restorations.

Technology is partnering with dentistry to generate computer-aided design and computer-aided manufacturing (CAD/CAM) for use in crown and bridge fabrication. Dentists and dental laboratory technicians are using CAD/CAM technology to increase the precision of individual restorations by capturing each tooth’s exact size, shape, and position. Digital impressions are more comfortable for the patient and less technique-dependent than customary alginate impressions. The resulting three-dimensional image appears on a computer screen, and the dentist can electronically draw the restoration design on the image instead of sculpting wax on a stone model. The details can then be transmitted digitally without distortion to the dental lab technician, who uses a CAD/CAM machine to mill a ceramic material into a detailed replica of the drawing. By looking at the same electronic image before manufacturing, the dentist and the dental laboratory technician can clearly communicate their needs and expectations for an accurate preparation that will result in a quality custom restoration. Digital impressions are also now making same-day crowns feasible.

See also Aging; Bone disorders; Cavities; Dental diseases; Dentistry; Dentures; Teeth.

For Further Information:

1 

Christensen, Gordon J. “Salvaging Crowns and Fixed Prostheses: When and How to Do It.” Journal of the American Dental Association 139 (December, 2008): 1679-1682.

2 

“Dental Bridges.” Cleveland Clinic Foundation, October 11, 2012.

3 

“Dental Crowns.” Cleveland Clinic Foundation, December 10, 2011.

4 

Jacobsen, Peter. Restorative Dentistry: An Integrated Approach. Malden, Mass.: Blackwell, 2008.

5 

“Porcelain Fixed Bridges.”American Academy of Cosmetic Dentistry, 2011.

6 

Stahl, Rebecca J., and Marcin Chwistek. “Dental Crown (Dental Cap).” Health Library, March 15, 2013.

7 

Walmsley, A. Damien, et al. Restorative Dentistry. 2d ed. New York: Churchill Livingstone/Elsevier, 2007.

8 

“What Are Crowns?” Academy of General Dentistry, January, 2012.

Citation Types

Type
Format
MLA 9th
Thivierge, Bethany. "Crowns And Bridges." Magill’s Medical Guide, 9th Edition, edited by Anubhav Agarwal,, Salem Press, 2022. Salem Online, online.salempress.com/articleDetails.do?articleName=MMG2022_0335.
APA 7th
Thivierge, B. (2022). Crowns and bridges. In A. Agarwal, (Ed.), Magill’s Medical Guide, 9th Edition. Salem Press. online.salempress.com.
CMOS 17th
Thivierge, Bethany. "Crowns And Bridges." Edited by Anubhav Agarwal,. Magill’s Medical Guide, 9th Edition. Hackensack: Salem Press, 2022. Accessed December 14, 2025. online.salempress.com.