A crown is a dental restoration that covers entire tooth . A crown is usually necessary when more than half of natural tooth above the gumline has been compromised by either trauma, decay or repeated large restorations. Crowns are also placed as the final restoration of a dental implant.
Crowns may be made of several different metal alloys, a combination of metal and porcelain, or more recently ceramics. For a long time Gold crowns were considered the best because they could be made to be as hard and as smooth as natural tooth. Metal crowns continue to have many applications.They were however predominantly limited to the back of the mouth due to aesthetics. Also over extended time and with uncontrolled tooth grinding you can wear a hole in a gold crown.
Porcelain fused to metal crowns solved that problem by allowing smooth white porcelain to cover the metal portion of the tooth. These "PFM"s have been around for about 60 years. They also have their applications.
There challenge is the the multilayer construction has an inherent weakness. Each layer is attached the other through very chemical bonds forged by high heat. These bands have the potential to sheer off and cause fractures that expose the thin layer of metal underneath. These PFM's are also prone to wearing holes in the chewing surface over lifetime of the crown.
The modern ceramic crowns offer superior aesthetics, strength and longevity over the metal crowns and PFM's. There crowns are made with tried and tested space aged materials that can be made to look like natural teeth while having strength that will far exceed the hostile environment of the our mouths
A veneer is a thin, custom-made, tooth-colored shell which is designed to cover the front side of teeth. Veneers correct a variety of tooth imperfections. Veneers can treat spaces between teeth and teeth that are chipped or worn, permanently stained, poorly shaped or slightly crooked. They are attached by removing a small amount of enamel from the tooth and permanently bonding the veneer to the tooth. Veneers are made of porceain and ceramic as well. Never metal.