The Difference Between E-Max & Zirconium Crowns and Making Them

The two most common digitally fabricated crowns for your teeth are E-max and Zirconia.  What’s the difference and which would be best for you?

E-max is Lithium Disilicate glass, an all-ceramic system.

  • It is one of the most aesthetically pleasing options, porcelain can be layered on it, creating incredible translucency and a very realistic looking tooth that matches with other natural teeth.

Zirconia is Zirconium Dioxide, a white, powdered metal oxide. It is also ceramic.

  • It is incredibly strong, resistant to wear, and difficult to crack.

Translucent Zirconia

  • Due to recent concerns about the lack of aesthetic appeal of zirconia (because of its density), dental supply companies have come out with more translucent zirconia.
  • This new iteration of translucent zirconia is not as strong as original zirconia, as the material that is added to make it translucent is less strong.

So, what do you want?  The e-max with its pleasing aesthetics looks great in the anterior (front teeth) resembling your real teeth so closely. The material is ideal for front teeth that are naturally thin and less opaque. The zirconia, with its strength make for great posterior (molars) teeth.  They don’t show much in your smile but have the great strength and durability to chew food.  If you suffer from bruxism (grinding your teeth) zirconium is the one to go with.

E-max crowns have a lifespan of approximately 10-15 years before they may experience a crack or fracture due to pressure put on the crown through grinding and a hard bite.  E-max crowns are more translucent compared to Zirconia crowns. The ceramic material allows more light to pass through. That’s a major advantage for creating teeth that look as natural as possible. The milling process used creates the perfect shape for your tooth.  A customized tooth crown is created from the digital impression made of your tooth.

The typical steps on fitting an e-max crown are:

  • First, the dentist performs an examination and cleans your teeth.
  • Then, using a small drill, the teeth are reshaped so that the crown can fit onto them.
  • Depending on the level damage or staining, a part of the tooth may be removed or drilled out. Sometimes the tooth reduction is negligible if you have very small teeth.
  • After this, the dentist takes a digital impression of your teeth with the help of a mold filled with dental putty. This is used as a cast for the fabrication of crowns.
  • For two or three weeks you might have to wear a temporary crown until the new one isn’t ready. The dentist completes the final fitting through dental surgery.
  • Lastly, after the fitting, the dentist does a final color check against the shade chart.

Zirconium crowns are highly prized for their long-lasting durability. But the hardiness of the crystal comes at a price. Compared to E-max’s lithium disilicate, zirconium is more opaque. Therefore, dentists recommend zirconium crowns for back teeth that require sturdy material that can survive a lot of biting and chewing. Zirconium is recommended for crowns with dark teeth underneath because the opaqueness hides the shadowing.

For a lab that practices digital dentistry, these two materials come in a disc shape which is inserted into a milling machine.  After a digital impression is taken of your teeth which is then sent to a computer with CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) software.  The tech designs the prosthesis (crown or bridge) which is then milled to exacting specifications to ensure it will fit the tooth with margins to be close enough to prevent food from being caught between the teeth or is easily removed by flossing, like your original teeth.  After the crown or bridge are milled from zirconia, it is then placed into an oven to be heated at high temperature (1600 degree Celsius) like clay is placed in a kiln to glaze and harden and when finished it is placed in your mouth over your tooth.  The heat process used to take 8 to 9 hours.  Columbia Dental just purchased a new sinter oven which has a high temp/short cycle that now does this process in twenty minutes.   E-Max is milled using a wet mill and therefore does not require the high temp oven.  This means your crown or bridge can be done while waiting in the office and be inserted into your mouth allowing you to leave with your prosthesis all on the same day.

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