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R&D Corner: What’s in the Zirconia Crowns You Place? Investigating the Raw Material

What’s in the Zirconia Crowns You Place? Investigating the Raw Material
John Bernhard, Senior Product Manager, Glidewell Dental

article by John Bernhard, Senior Product Manager, Glidewell Dental

chairside@glidewelldental.com

In just one decade, the long-standing workhorse of restorative dentistry, the PFM, has been dethroned by monolithic zirconia as the go-to material for full-coverage restorations. This sea change began in 2009, and continues to be driven by the swift, widespread adoption of BruxZir® Solid Zirconia from Glidewell Dental, a company with a nearly 50-year history of producing high-quality restorations and advanced dental technologies.

As a result of the rapid success of BruxZir zirconia, an explosion of zirconia brands has hit the dental market, many of them imported from industries outside of dentistry. Now, dentists are challenged to wade through the noise, and to distinguish the fundamental characteristics required for prescribing the best zirconia restorations for their patients.

To understand what has made the brand unique, it’s important to examine the qualities that make BruxZir Solid Zirconia the No. 1 material of choice for crown & bridge applications — an investigation that leads straight to the source.

A Natural Mineral Harvested from the Earth

Perhaps the most important attribute that we certify is that all zirconia manufactured by Glidewell is effectively biocompatible, pure and free from harmful radiation. Although it’s not widely known, zircon, the mineral from which zirconia is derived, is actually radioactive — a characteristic that dentists and patients would rather avoid.

Zirconia used for dentistry is actually called zirconium dioxide (ZrO2). It is a compound powder refined from naturally occurring zircon ore, which is harvested from the earth by a handful of large biochemical conglomerates around the world. It is similar in properties to other ores that are radioactive. As a result, the zircon is processed and purified to remove Uranium and Thorium from the material before it can be further processed for use in the oral cavity.

Since the advent of BruxZir zirconia as a material for restorations, Glidewell has developed and employed some of the most rigorous protocols to verify that BruxZir Solid Zirconia not only is esthetic, durable and clinically validated, but also adheres to best practices for ensuring safety for your patients.

In fact, unless the zirconia manufacturer reaches the highest standards of refinement, purifying and processing, and provides the documentation and certifications to prove it, there is risk that a dentist could unwittingly place a radioactive zirconia crown in his or her patient’s mouth. Therefore, it’s imperative to examine the source of the raw zirconia powder.

Tosoh Corporation adheres to rigorous guidelines to purify zirconia powder for BruxZir Solid Zirconia restorations. Upon production, Tosoh tests the chemical characteristics of the zirconia powder as well as a sample sintered body from each lot — and a sample of every lot produced for Glidewell Dental is sent to a German institute for testing and certification.

From the Ground to the Refinery

The process to purify raw zirconium is expensive and requires a high level of expertise and competence. Not all zirconia providers have the capability to test or certify that their zirconia is free from impurities. When Glidewell Dental began developing BruxZir zirconia, we sought out the most experienced zirconia producers in the world. This journey led Glidewell Dental’s R&D team to Tosoh Corporation, a Tokyo, Japan-based pioneer in the manufacture of zirconia powder. Tosoh demonstrated a level of rigor and quality that was unsurpassed among zirconia providers. Furthermore, the team’s willingness to work hand in hand with Glidewell Dental in the development and ongoing improvements to BruxZir Solid Zirconia served as the foundation for an ongoing collaboration that continues to this day.

Glidewell Dental uses innovative processes to refine Tosoh zirconia, increasing the strength and translucency properties of BruxZir crowns & bridges.

Glidewell Dental’s R&D team has been instrumental in the initial and continued development of BruxZir zirconia. To date, in just 10 years of existence, more than 18 million BruxZir restorations have been delivered, underscoring the clinical success of the product.

Collaborating to Set the Standard for High-Quality Zirconia Restorations

From the first meetings with Tosoh, one of the requirements from Glidewell Dental was establishing that BruxZir Solid Zirconia was made from zirconia powder that was certified as free from any impurities and radioactivity. The team utilized very strict incoming material acceptance standards, establishing tests for the powder as well as the sintered body for every lot of material produced and rejecting nonconforming lots. Glidewell chose to partner with Tosoh because the company’s capabilities were not limited to the manufacture of powder, but also expanded to the technology used to test the raw material as well as the final sintered body in ways that no other zirconia provider could demonstrate.

Tosoh, as a leading chemical firm, had taken steps to establish in-house technology to purify zirconia powder to demanding internal standards, and to eliminate the radioactive isotopes in raw zirconia. Upon powder production, Tosoh tests the chemical characteristics of the zirconia powder as well as a sample sintered body from each lot. Additionally, a sample of every lot produced for Glidewell is sent to a German institute for radioactivity testing and certification. Test reports are provided directly to Glidewell Dental, which are reviewed and certified before the zirconia is used in the manufacture of BruxZir Solid Zirconia.

BruxZir crowns are fabricated using advanced engineering equipment to ensure that each customized crown consistently meets the exacting requirements of doctors and patients.

A BruxZir Solid Zirconia block is milled using state-of-the-art CAD/CAM technology. The sintered crown is hand-painted by an experienced, certified dental technician, and the final crown is scrutinized by the quality assurance supervisor before it is sent to the doctor.

Jim Glidewell, CDT, founder and CEO of Glidewell Dental, has dedicated nearly half a century to his mission to raise the bar on the quality of restorations dentists prescribe for their patients. “BruxZir Solid Zirconia is one of the most significant technological advancements in dentistry in the last 50 years,” said Mr. Glidewell. “BruxZir has almost single-handedly replaced the long-standing PFM restoration — which had been the standard for decades — as the material of choice for crowns. In fact, in just 10 years of existence, more than 18 million BruxZir restorations have been delivered, underscoring the clinical success of the product. As a ceramist, I can attest that this success is attributed largely to the distinctive characteristics of the formulation of BruxZir itself, a material unlike any other available in dentistry.”

Glidewell Dental collaborated with Tosoh Corporation, a leader in high-purity zirconia powder, to develop and release BruxZir Solid Zirconia. Shortly after its introduction, Jim Glidewell, CDT, accepted Tosoh Corporation’s “Best Product Innovation Award” from Yutaka Nakamura, president of Tosoh America, in Newport Beach, California.

Glidewell Dental’s 66-person R&D team was instrumental in the development of BruxZir zirconia and used innovative processes to refine Tosoh zirconia to a significantly reduced grain size, which increases the strength and translucency properties of BruxZir Solid Zirconia. This team, which includes Ph.D.s in material science and engineering, dentists, and dental technicians, used the latest material advancements in conjunction with proprietary, groundbreaking processes to create dental restorations that exhibit lifelike vitality and chip-proof strength.

Tosoh and Glidewell have anchored their relationship with frequent, open communication between the lab and Tosoh’s R&D and quality assurance teams. This has led to the exchange of ideas, investigations into the feasibility and benefits of ongoing innovations, and delivery of new zirconia products to better serve the needs of the dental community.

With more than a decade of clinical research and experience driving BruxZir Solid Zirconia innovations, Glidewell doctors and scientists continue to pioneer restorative solutions to further serve the needs of the dental community.

Conclusion

In 2009, Glidewell spearheaded inventive processes that repurposed how zirconia was used in dentistry, and BruxZir Solid Zirconia forever changed the way dentists prescribed restorations. Through a relentless pursuit of quality and excellence, the Glidewell R&D team, together with scientists at Tosoh, have gone to painstaking lengths to make BruxZir Solid Zirconia a biocompatible, contemporary all-ceramic restoration with advanced physical properties for a wide range of clinical applications. As we continue to develop and innovate zirconia solutions, we will always measure ourselves and our BruxZir restorations against the highest standards — beginning with the pure zirconia source and ending with the final restorations delivered to millions of patients around the world.

Chairside Magazine: Volume 14, Issue 2

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