FIXED BRIDGE
A fixed bridge replaces or spans the space where one or more teeth have been lost. A fixed bridge is attached to natural teeth (abutments). It is cemented into place and can only be removed by a dentist. The abutment teeth are crowned to provide strength. The ponic, or artificial tooth, is the part of the fixed bridge that replaces the missing tooth or space between the abutments. The ponic is fused to the abutments to form one piece that is cemented or bonded into place in the mouth. These restorations prevent collapse of the mouth and movement of teeth. Fixed bridges have special instructions for proper home care, which will be explained by the dentist or dental assistant upon completion of treatment.
source: http://www.dentistryatwinbury.com/dental-health-chagrin-falls-oh/dental-dictionary.html

A dental crown is a tooth-shaped “cap” that is placed over a tooth — to cover the tooth to restore its shape and size, strength, and improve its appearance.

The crowns, when cemented into place, fully encase the entire visible portion of a tooth that lies at and above the gum line.

Why Is a Dental Crown Needed?
A dental crown may be needed in the following situations:

To protect a weak tooth (for instance, from decay) from breaking or to hold together parts of a cracked tooth
To restore an already broken tooth or a tooth that has been severely worn down
To cover and support a tooth with a large filling when there isn’t a lot of tooth left
To hold a dental bridge in place
To cover misshapened or severely discolored teeth
To cover a dental implant
To make a cosmetic modification
source: http://www.webmd.com/oral-health/guide/dental-crowns

Fixed Bridge : Porcelain fused to Tilite

– a white metal which eliminate the black gum effect caused by metal alloy.