A dental crown is a tooth-shaped “cap” that is placed over a tooth or a dental implant.
The dental crown, when cemented into place, fully encases the entire visible portion of a tooth that lies at and above the gum line.
A dental crown is done when you still have a root but all the enamel is either fractured or the tooth has had a root canal. When a tooth has had a root canal treatment, the blood vessel has been removed from the tooth, the tooth dries out and then you need a crown over it. Crowns don’t replace a missing tooth. Crowns replace missing enamel and teeth that have been destroyed by decay or breakage.
Each one of your natural teeth is like a work of art and will have multiple colors running through it. It’s like a pearl or an opal; it has opalescence. If you hold a pearl up to the light and the light shines through it, you’ll see rainbow colors. When I create a crown, I want it to have the same properties as natural teeth.
We previously used only porcelain fused to a metal crown to achieve the effect of a tooth color similar to your other teeth. However the metal under the porcelain would stop the transmission of light through the tooth. As a result the tooth would look different than your other teeth when light was shining on your teeth.
I now also use zirconia or dilithium silicate crowns. There is no metal in these types of crowns. The lack of metal means that when you smile, light will shine all the way through the crown just like a natural tooth. Porcelain is layered over zirconium or dilithium silicate because then the color of the porcelain can be changed with different gradations of shade to match your other teeth.
I work with a good ceramicist; a person who lives about a mile from my office who makes my crowns. He will come to my office and look at my patient’s teeth when the replacement is in a critical area so he knows how to color the porcelain over the zirconium or dilithium silicate crown to make it look like the rest of the teeth.
Zirconium vs. Gold
Gold had been the traditional best crown material for the last 100 years. It is strong and typically will last many years. I will still do gold fillings when they are requested.
I like the zirconium crown better because I can make it look like a natural tooth and polish it as smooth as I am able to polish the gold. Zirconia seems now to be the strongest material available and the material most similar to enamel (actually stronger than enamel). You can wear a hole through gold (although it takes 20-30 years) while zirconium does not seem to wear.
Zirconium is a good temperature insulator, will not conduct hot and cold, is not soluble and no one is allergic to it. Gold is not as good of an insulator.