March 13, 2021
When teeth have lost a significant portion of their structure to decay or trauma, a dental crown (sometimes referred to as a cap) is indicated for long term protection and functional rebuilding of the tooth. This treatment has been done for thousands of years. Crowns and bridges go back to the ancient Etruscans in about 200 AD and, as with everything else, the process keeps getting refined and materials keep changing.
Early crowns were usually made of metal, gold being the most common. Gold is the most versatile metal since it can be worked and formed in so many ways. Crowns have been made of hammered gold that was formed on models and then later, cast gold that is formed from a mold created from a wax pattern. This “lost wax technique” was also adopted by jewelry makers. For many years and in many cultures gold crowns were a status symbol of sorts, showing that you had the means to have dental treatment done.
As acrylic resins became available, gold crowns were made with cutouts on the outside surfaces to allow acrylic facings to adhere and give the appearance of a tooth colored crown. These achieved a fair result but were prone to staining of the plastic and breakage and de-bonding from the gold. Newer tooth colored fillings could often replace the broken acrylic with better strength and appearance.
With the development of dental porcelain, the porcelain jacket crown was developed and then the porcelain fused to gold crown. The jacket crowns were not very close fitting and were very prone to fracture. The porcelain on metal technique came of age in the early 1970’s and has been the standard of care since then. That is changing now.
Newer ceramic materials have revived all ceramic crowns and they are stronger and more esthetic than ever.
The newest ceramic crowns are amazing products. They conduct light almost identically to tooth enamel and dentin and so look realistic in almost any lighting. Without the need for metal underneath, there is no telltale dark rim at the gum line where the crown ends and because they are bonded to tooth structure, they can be made thinner and allow for more conservative tooth preparation.
Some of the ceramics are even strong enough to fabricate a bridge to replace a missing tooth. This has lead to some very exciting predictions about the future of dental materials and treatment options for our patients.