Why zirconia?

March 21, 2012

At THE DENTAL ADVISOR, our group has been researching and tracking all-ceramic restorations for 28 years. As ceramics have evolved, there is a move toward stronger and more esthetic materials.

At THE DENTAL ADVISOR, our group has been researching and tracking all-ceramic restorations for 28 years. As ceramics have evolved, there is a move toward stronger and more esthetic materials.

As we educate both doctors and laboratories on the evolution of all-ceramic materials, the focus lately has been on zirconia versus lithium disilicate. Depending on the clinical situation, both materials offer excellent esthetics and provide long-lasting results. So why all the hype?

Currently, zirconia has the highest flexural strength of any all-ceramic material. The advantages of zirconia over other materials are it is biocompatible, it is less expensive than using metal and it offers excellent esthetics.

Probably the most popular question posed to us at lectures and on our website is about zirconia fracture. It has been said many times, but should be clarified that the reported fractures are of the overlaid porcelain, not the zirconia substructure. Early on, fractures were reported because of a number of factors: poor coping design, improper mixing of overlay porcelains, improper firing, and poor preparation by doctors.

In response to the fracture and chipping issue, considerable attention has been given to educating both doctors and technicians on the use of the material. In fact, laboratories are now realizing that with the fixed price of zirconia, support of porcelain can be emphasized during substructure design, rather than minimizing metal to keep restoration costs down.

In addition, because of zirconia’s excellent biocompatibility and strength, we are starting to see more and more interest in and use of full-contour zirconia restorations in lieu of full-contour metal or metal occlusal restorations. 

THE DENTAL ADVISOR is proud to be the only organization worldwide that has clinically tracked restorations on 3M ESPE’s Lava zirconia for the past 7 years.  We recently published the study of more than 1,500 porcelain fused to zirconia (PFZ) restorations placed during the past 7 years. Five hundred seventy-four were recalled for this study and highlights from the results include:

Resistance to fracture and chipping

Of the recalled restorations, 16 (2.7%) were replaced because they received a rating of 1 or 2 out of 5. In these cases porcelain delaminations were significant enough that they could not be acceptably smoothed or polished. Thirty-five restorations (6%) received a rating of 3 or 4. These were chipped restorations that either did not need any smoothing or polishing or could be polished and smoothed satisfactorily.

Esthetics

The majority of the recalled restorations had excellent esthetics, and 57 restorations (10%) had a good to very good rating.

Resistance to marginal discoloration

More than 95% of Lava restorations received an excellent rating for resistance to marginal discoloration. During the 7-year evaluation, only 2.8% of the restorations exhibited slight graying at the margins.

Wear resistance

More than 96% of Lava restorations received an excellent rating for resistance to wear. A small number (3.2%) of the recalled restorations exhibited some wear of the overlaid ceramic at 7 years.

For the full article go to: dentaladvisor.com/clinical-evaluations/evaluations/3m-espe-lava-crowns-and-bridges-7-yr.shtml

About THE DENTAL ADVISOR

For nearly 30 years, THE DENTAL ADVISOR has been reporting on dental materials and equipment for the dental profession. The Long View is designed to report on clinical performance over time. This is a key metric desired by clinicians and technicians when choosing a product.

With doctors often asking questions regarding the right material to choose in a given clinical situation, THE DENTAL ADVISOR is available as a resource and would be glad to assist you. Visit THE DENTAL ADVISOR at dentaladvisor.com or send questions via e-mail to: info@dentaladvisor.com.

About Apex Dental Milling

Apex Dental Milling is a premier dental milling facility operating multiple dental CAD/CAM systems and capable of working with the ever expanding range of materials. As a partner of THE DENTAL ADVISOR, Apex Dental Milling offers valuable insight and consulting on CAD/CAM from the laboratory viewpoint.