While gold continues to be an excellent material for making crowns, many patients object to the gold color and temperature sensitivity of these crowns. Historically, patients have pushed for a strong, esthetic, long lasting natural looking all porcelain restoration. There is now porcelain on the market that has these characteristics. The material is made by Ivoclar Vivadent Inc. and is called Emax, which is a lithium disilicate glass ceramic.
Emax is monolithic in nature meaning the material characteristics are the same all the way through the material. Other porcelains, such as the very popular Zirconia porcelain uses a very strong substructure and layers esthetic porcelain over this substructure. The finished result is a very nice looking porcelain crown with a flexural strength of 90 mPa. In contrast, Emax has a flexural strength of 360-400 mPa. Other popular porcelains such as Finesse All Ceramic, Authentic, VitaMark II, Hera Sun Press, GC Intial PC and Cergo Press have a flexural strength that ranges from 114-150 mPa. These tests showed Emax has a flexural strength 3-4 times stronger than other popular porcelains. In load testing until failure, Emax was again the strongest, and was 40% stronger than a traditional porcelain metal crown.
Dentists have known for a long time that porcelain can excessively wear opposing tooth enamel. In contrast, using an OHSU machine to simulate 5 years worth of wear, Emax porcelain showed a very low wear rate, lower in fact than enamel itself and much lower than other porcelains. Further, in cytotoxic testing in accordance with ISO guidelines, Emax was found to be very biocompatible.
Patients who want porcelain restorations should definitely consider the new Emax porcelain. It has beautiful esthetic properties, is 3-4 times stronger than other porcelains, and will not wear opposing tooth structure as traditional porcelains do. This is definitely the porcelain of choice of Dr. James M. Austin. He can be contacted at 425 643 5778 or www.familydentalcareofbellevue.com