The Keys to a Strong, Reliable Zirconia Bond
ZirClean nonabrasively cleans the zirconia bonding surface after try-in, while Z-Prime Plus contains two monomers to enhance the bond strength between zirconia and resin cements
When it comes to choosing the ideal restorative material, the closer we can get to nature, the better. For many lab techs and doctors, the biocompatibility, strength, and fracture resistance that zirconia provides is as good as gold. While some dentists may be convinced that bonding to zirconia is unpredictable, Rolando Nuñez, DDS, MSc, would have to disagree. “When a proper protocol is followed, bonding to zirconia can be achieved in a predictable and consistent fashion.”
According to the clinician, who serves as BISCO’s Manager of Clinical Marketing, zirconia has become a popular material choice for several reasons, including its strength, superior physical properties, and durability.
While studies show zirconia is quite popular in the posterior region, clinicians also find success using it for anterior crowns. “In recent years, zirconia has evolved to become more esthetically pleasing, so its clinical applications have expanded to areas with higher esthetic demands,” said Dr. Nuñez.
A Proven Bond to Zirconia
This surge in zirconia popularity led to BISCO's development of Z-Prime Plus, a single-component primer that enhances adhesion between indirect restorative materials, such as zirconia, and resin cements. Launched in 2009, it contains both MDP, a phosphate monomer, and BPDM, a carboxylate monomer—a unique combination that allows for a synergistic effect, resulting in high bond strengths.
“While developing Z-Prime Plus, we discovered that MDP bonds to zirconia. We achieved bond strength values, which is physical proof of the chemical reaction, as well as contact angle, which is visual proof of the reaction. But we still needed chemical proof,” said Dr. Nuñez. The last piece of the puzzle was a secondary ion mass spectrometry (SIMS) test conducted at Northwestern University in Chicago—30 miles from BISCO headquarters in Schaumburg, IL—that confirmed the chemical bond between MDP and zirconia.
A Clean & Pristine Bonding
Surface While BISCO introduced Z-Prime Plus over a decade ago, it would take a second product launch to truly tackle the issue of zirconia debonding. When Z-Prime Plus was being developed, zirconia bonding was achievable in the lab, but out in the fi eld, many clinicians were struggling with debonding issues, said Dr. Nuñez.
“We discovered that the main reason for these debonding occurrences was saliva contamination after try-in, which hinders bonding," he said. So, BISCO got to work on a solution. “The main idea behind the development of ZirClean was to design a product that was effective, easy to apply, and that would provide a clean and pristine zirconia bonding surface.”
BISCO pored over the literature and tested other materials and techniques, ultimately discovering that an alkaline pH above 10 eliminates the contaminated saliva layer from zirconia. It also exposes the bonding site so an MDP-containing primer or cement can react and generate a chemical bond. After intraoral try-in, ZirClean cleaning gel will nonabrasively clean the zirconia bonding surface and wash off easily before cementation.
“Zirconia is a wonderful restorative material that came to dentistry to change it in a good way,” said Dr. Nuñez. “And now, with the esthetic possibilities of 4Y and 5Y types of zirconia, the possibilities have increased—making it the material of choice for a growing number of restorative dentists.
