Tales from the Bench: Straight Talk on Zirconia Fractures By Paul Lindsey This quarterly feature will highlight case corrections and tips from the bench that optimize the results learned from cases before you! Over the course of the last year, there has been much discussion about the reports of Lava and zirconia failures, including fracturing and delaminating porcelain. Since, as a laboratory Gold Dust had a history of success in recommending Lava framework and copings for strength, we made it our mission to investigate the reports and analyze our internal data on remakes. Interestingly, the only commonality among our remake numbers is that the doctors were not reporting catastrophic failure (coping fracture) but the chipping of porcelain applied to the substructure. We queried our remake rate for the last 36 months and found a 2.6% remake or failure rate was considered within normal limits and comparable to PFM remake rates within the same 3 year period. After multiple meetings with manufacturers including Ivoclar, 3M and Jensen, and understanding a controversial report from CRA, we attended a comprehensive lecture on this very subject with a Prosthodontist and Associate Professor in the Biomaterials and Advanced Prosthodontic department to better understand the reports through the marketplace about “Lava Failure.” Dr. McClaren maintains a private practice where he also produces all of his own ceramics. Dr. McClaren and a well-known fractologist (a scientist who specializes in the fracturing of materials!) developed a study on the potential of zirconia fractures and causes. Findings, consistent with our internal reports, COPINGS had not actually failed or displayed evidence of fracture. The stacked or pressed porcelain in less than 3% of cases produced in lab, had reported chips and fractured. Primary causes, as reported by Dr. McLaren’s study include: Unsupported porcelain over coping caused by preparation design. Zirconia and the layering porcelains were found to have significantly different cooling rates that could cause micro-fractures in porcelain that later develop into vertical cracks or fractures. A very specific protocol was recommended and instituted at Gold Dust and all laboratories across the country to rectify the cooling temperatures, to provide consistency in the product, and to eliminate the potential for porcelain to chip in fully supported designs. This adjustment to fabrication was adopted by 3M as a company and instituted in October of 2009. For the last 6 months, our remake ratio on Lava units fabricated since October has been less than .5%. For strength and aesthetics, we routinely recommend Ivoclar’s e.Max Zirpress to Lava. We will stack porcelain to Lava as well however there is a compromise in strength with stacked porcelain vs. pressed. At a recent training seminar with 3M ESPE the indications of pressed ceramics over Lava had significantly less reports of fracture than stacked over Lava. Gold Dust remains committed to providing the best restorative options available, and for many applications zirconia substructure is an ideal application. Should you have any questions regarding what is the best material for your next case, don’t hesitate to contact me: • Email: paul@golddustdental.com • Phone: 800.513.6131 • Skype: golddust.paul Click here to download 3M Espertise™ Scientific Facts for more information on this subject.

Gold Dust Dental • 2242 S. McClintock Ste 1 • Tempe, AZ 85282 golddustdental.com • 800.513.6131