Over one hundred years ago, dentistry made its first attempt to help beautify smiles. It was the beginning of the use of ceramics, or porcelain, to help rebuild a broken down tooth. As the years went by, improvements were made in cosmetics, but the strength was still lacking. The restorations were prone to cracking until the 1950’s when a metal substructure was added to this porcelain “jacket.” This improved the strength tremendously, but the restorations were not as esthetic, due to the opaque layer that had to be added to block out the dark grey metal. Although chipping of the porcelain still periodically occurred, this crown has been the mainstay of crown restorations and is still used by dentists today.
Recently, two new innovations have come on the scene to eliminate the metal substructure and have many times the strength of the porcelain jacket. The first is “lithium disilicate” and it has incredible esthetics with a flexural strength of 360-400 megapascals in order to resist chipping and cracking. These restorations mimic tooth structure incredibly well. The second is monolithic zirconia oxide, developed for individuals who grind and clench their teeth. It almost rivals metal in strength plus it has a flexural strength of up to 1465 megapascals.
Both of these new discoveries can be made with the help of a computer and the cad-cam technique. A digital picture is taken and then the crown is precisely milled from a solid block. With zirconia crowns, an extra step of sintering (super heating) the crown for hours in a 1530 degree Celsius oven gives it high strength and chip resistance. They are then glazed for a smooth surface to inhibit plaque formation. As strong as these restorations are, they are extremely kind to the teeth that they chew against in the mouth since porcelain is four times as abrasive as these extraordinary new crowns.
Ask your dentist whether these new restorations may be right for you.
Dr. Herbert Schneider has been recognized for his work with fellowship awards from the Academy of General Dentistry and the American Endodontic Society. He also holds a prestigious Mastership from the World Clinical Laser Institute. Dr. Rachel Jacobs joined the practice in 2006. Her calm, yet precise manner makes her a hit with both adults and children. Both Dr’s are certified in the uses of 3 different clinical lasers.
By Dr.Herbert Schneider