A bridge is prosthetic that replaces a missing tooth/teeth; it is permanently cemented to a tooth or teeth in front, and in back, of the missing tooth/teeth it is replacing.
A bridge looks like real teeth; in many cases it even looks better than the original teeth did before the bridge was placed. This is because it can be made to more ideal specifications, with regard to shade, shape, and function.
Bridges are placed by preparing the tooth/teeth in front of the missing tooth, or teeth, and preparing the tooth/teeth behind the missing tooth/teeth. These preparations are the same preparations that are done for single unit crowns. The only difference is these teeth must be prepared with a path a withdrawal and insertion; this is called parallelism. To decide how many natural teeth must be prepared to properly construct a bridge which will last the normal life expectancy, dentists follow a law of physics called Ante's Rule. It outlines how a structurally-sound bridge needs to be constructed.
Bridges are considered "permanent" restorations, in that they are cemented on the teeth and do not come in-and-out, but are permanently affixed.
The average lifespan of a high-quality, properly prepared and fabricated bridge is approximately 15-30 years. The better the doctor that prepares the teeth, and the better the laboratory that fabricates the bridge, the longer that bridge should last.
While bridges themselves do not get cavities, the interface between the bridge and the natural teeth on which the bridge rests (AKA: the margin) can get cavities, and is the primary area where cavities do form after bridges are placed. A patient can aid in increasing the lifespan of a bridge by brushing it 3x daily, and flossing under it and around it nightly. Many times a WaterPik is a desired adjunct to regular flossing, as it ensures a thorough cleaning under the pontics (AKA: fake teeth) of the bridge. Keeping your new bridge clean should be of primary importance.
Once the bridge is permanently cemented, it should be used as you would use all other teeth in your mouth, unless your dentist gives you other instructions. Today's bridges are made of all tooth-colored materials and most have no metal. Here at Hoffman Dental, Dr. Brian Hoffman does not use any metal in his crowns, bridges, inlays, onlays, or fillings. The substructure of bridges is primarily zirconia (AKA: man-made diamond material), or alumina. These materials have hardness strengths of 400-600 MPa for alumina based cores, and Zirconia based cores have strengths ranging from 900-1200 MPa. This is exceedingly strong and durable, plus they better mimic the metamerism (AKA: natural look and luster) of natural teeth.