There are many different kinds of crowns to choose from.
For this blog post, I would like to talk about EMAX crowns/veneers. EMAX is a brand name from Ivoclar Vivadent, not a specific restoration. It's made out of lithium disilicate and zirconium oxide (Zn).
-How it is made-
EMAX comes in small blocks for a conventional wax & press technique and is also available in blue block(pre-sintered) for CAD-CAM. EMAX can be waxed and pressed, so you will be able gain accurate fit and increased strength (400MPA). EMAX also can be designed with CAD and milled in the blue block stage. Through this method, there will be a very good fit, but slightly weaker strength (360MPA) compared to the wax & press technique.
EMAX is considered to be the best match for natural teeth because of its transparency. Lately, Zirconia has an improved opaque appearance with high translucency. In my opinion, however, EMAX offers the best combinations of translucency, opacity, chroma, hue, and value by far.
Because chemical bonding can be done with an EMAX restoration, conservative veneers (less tooth is adjustments) can be made out of EMAX. Back in the old days, feldspathic veneers made out of porcelain powder were the only option for ceramic veneers. They looked very nice, but were technically hard to fabricate and were easily chipped. In the 1980's, the first pressable ceramic with leucite created 'Empress' (a brand name). It was introduced for veneers that are now stronger and easier to fabricate. Nowadays, I have observed that EMAX generally provides patients with the strongest, bondable veneers.
I do not believe that 400MPA is enough for some patients in certain situations. Due to this limited strength, I would not recommend that bridges (which connect the space between two teeth) be made in EMAX at this time.
The materials in dentistry are always changing at a rapid pace. I remember when porcelain crowns (restorations without a metal core) were being introduced into dentistry 25+ years ago along with many claims. Some of these claims came true, but a lot of them did not work as advertised. For the past 10+ years now, in my opinion, EMAX crowns have provided an excellent service for many of my patients with its natural looks and fracture resiliency, especially in the anterior of the mouth.
Below are two examples of the material in use, demonstrating the possible aesthetic improvements.
-Braeside Dental Center