What Is the Compostion of Porcelain Dental Crowns?
Whether you have serious decay or need a root canal or implant, a crown becomes a necessary prosthetic in dentistry. Although metal crowns are the strongest, porcelain crowns are the most aesthetically pleasing and mimic real teeth. They're scientifically known as feldspathic porcelain crowns.
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Silica
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Silica comprises 65 percent of the porcelain in the porcelain crown. The silica is present in the form of feldspathic glass (hence, the name of the crown) and crystalline quartz, extending the translucent nature of porcelain.
Aluminum Oxide
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Approximately 10 to 25 percent of a porcelain crown is aluminum oxide, which is a component of feldspathic glass. This component serves as the strengthener of the glass structure and diffuses light in the crown, creating an element of opacity.
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Boric Oxide
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Boric oxide makes up approximately 5 to 10 percent of a porcelain crown. Its main purpose is to strengthen the glass to resist pressure and shock, as well as drastic changes in temperature, which can affect glass. For example, if you drink a cup of hot coffee, and then drink cold water, the boric oxide prevents any cracking in the porcelain crown.
Other Oxides
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Potash and soda in porcelain crowns reduce the melting temperature overall. Because all feldspathic porcelain crowns must endure a baking process in development, manufacturers must adjust the melting point of glass to prevent it from running to the bottom of the kiln. Manufacturers also add other metal oxides for color adjustments and translucency.
Warning
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Keep in mind that 100 percent porcelain crowns, being primarily glass, are weak in structure. Dentist almost never use them for the back teeth; they use them for anterior teeth solely for aesthetic reasons. With the advent of Cerec and Empress crowns, along with other new all-glass improvements, other crowns may be worthy of consideration prior to investing in an all-porcelain crown.
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